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Meeting Abstracts  |   March 2004
Nuclear Factor κB and Anesthetic Preconditioning during Myocardial Ischemia-Reperfusion
Author Affiliations & Notes
  • Caiyun Zhong, M.D.
    *
  • Yamei Zhou, Ph.D.
  • Hong Liu, M.D.
  • * Postgraduate Researcher, † Postdoctoral Fellow, ‡ Assistant Professor.
  • Received from the Department of Anesthesiology and Pain Medicine, University of California, Davis, Davis, California.
Article Information
Meeting Abstracts   |   March 2004
Nuclear Factor κB and Anesthetic Preconditioning during Myocardial Ischemia-Reperfusion
Anesthesiology 3 2004, Vol.100, 540-546. doi:
Anesthesiology 3 2004, Vol.100, 540-546. doi:
VOLATILE anesthetic preconditioning (APC) has been shown to promote protection from myocardial ischemia–reperfusion (IR) injury in a fashion similar to that of ischemic preconditioning (IPC). 1,2 Several signaling pathways are activated in response to myocardial IR injury. Nuclear factor (NF) κB is a pivotal transcription factor that has been shown to play a key role in oxidative stress and inflammatory response and is activated during IR. Activation of NF-κB induces expression of a variety of gene products of which cytokines, chemokines, and adhesion molecules are implemented in IR injury. 3,4 The increased concentrations of these inflammatory mediators will contribute to myocardial IR injury. 5 
Nuclear factor κB is typically composed of p50 and p65 heterodimers. Under normal physiologic conditions, NF-κB is maintained in an inactive form in the cytoplasm by its inhibitors, IκB-α and other members of the IκB family. On activation of IκB kinase, IκB is phosphorylated, leading to a dissociation of NF-κB and IκB, as well as ubiquitination of IκB and consequent degradation of IκB by proteasomes. IκB kinase can be activated by numerous factors, such as reoxygenation, reactive oxygen species (ROS), cytokines (tumor necrosis factor [TNF]α, interleukin [IL] 1), and ischemia. When dissociated, NF-κB can translocate to the nucleus and bind to consensus sites in promotor or enhancer regions of target genes to initiate transcription. 6–8 It has been reported that myocardial IPC attenuates NF-κB activation and reduces the expression of inflammatory mediators, which decreases myocardial IR injury. 5 Because APC also protects myocardium from IR injury 2 and no data on the relation between APC and NF-κB are currently available, we tested the hypothesis that APC attenuates the activation of NF-κB and subsequently suppresses the expression of NF-κB–regulated inflammatory genes during reperfusion, such as TNF-α, IL-1, intercellular adhesion molecule (ICAM) 1, and inducible nitric oxide synthase (iNOS), all of which contribute to decreased myocardial IR injury.
Materials and Methods
Preparation of Isolated Hearts
The study protocol was approved by the Animal Care Committee of the University of California, Davis (Davis, California), and all experiments were conducted in accordance with guidelines of animal care from the National Institutes of Health.
Hearts were obtained from male Sprague-Dawley rats (weight, 250–300 g). Anesthesia was first induced with an intraperitoneal injection of sodium thiopental (50–75 mg/kg) along with 1,000 U heparin. Sodium thiopental was chosen for initial anesthesia because this drug has been shown not to influence preconditioning. 9 The heart was excised and placed in an ice-cold solution of Krebs-Henseleit buffer. It was then cannulated and Langendorff perfused with Krebs-Henseleit buffer (127 mm NaCl, 4.7 mm KCl, 1.25 mm MgCl2, 2.5 mm CaCl2, 25 mm NaHCO3, 10 mm glucose) at a perfusion pressure of 140 ± 10 cm H2O at 37 ± 0.5°C. The perfusate was continuously oxygenated with 95% O2–5% CO2. Pacing wires were placed in the right atrium after cannulation.
Experimental Design
Nine rats were randomly assigned to each of the three groups: (1) the control group: 130 min of continuous perfusion; (2) the IR group: 30 min of equilibration, 15 min of baseline, 25 min of global ischemia, 60 min of reperfusion; and (3) the APC + IR group: same as the IR group except 10 min of sevoflurane exposure followed by a 5-min washout was included immediately before 25 min of global ischemia. Sevoflurane was delivered at 2.5% to the gas mixture via  a standard Sevotec5 variable bypass vaporizer (Datex-Ohmeda, Milwaukee, WI) to reach a final concentration of 0.4 ± 0.02 mm. Global ischemia was induced by stopping all flow to the heart. Atrial pacing at 5 Hz was used during all phases of the experiment except global ischemia. Any episodes of ventricular fibrillation were mechanically converted when they occurred.
Preparation of Heart Homogenates and Microsomal and Nuclear Extracts
Immediately after reperfusion, three hearts from each group were frozen in liquid nitrogen and subsequently homogenized in ice-cold Tris-HCl buffer (25 mm Tris, 1 mm EDTA, 10% glycerol, 1 mm DTT; pH 7.4) with a glass homogenizer. The homogenate was centrifuged at 10,000 g  for 20 min at 4°C. The supernatant and sediment fractions were separated. The supernatant obtained as described above was further centrifuged at 105,000 g  for 75 min. The microsomal pellet was suspended in 0.05 m Tris-HCl buffer, pH 7.4, with 0.25 m sucrose. The supernatant and microsomal extracts were placed in aliquots and stored at −80°C. The crude nuclear fraction in the low-speed centrifugation was collected and washed three times with homogenate buffer containing Triton X-100, followed by washing one time without Triton X-100. Nuclear protein was extracted with buffer C (20 mm HEPES, 25% glycerol, 0.42 m NaCl, 1 mm EDTA) by centrifuging at 50,000 g  for 30 min. Protease inhibitor cocktail was added into the homogenizing and extract buffer. Protein concentrations of the extracts were measured by means of a modified Bradford assay according to the manufacturer’s instructions (BioRad, Hercules, CA) using bovine serum albumin as a standard.
NF-κB–DNA Binding Activity
Electrophoretic mobility shift assay was performed to determine NF-κB–DNA binding activity. The oligonucleotide used as a probe (Promega, Madison, WI) was double-stranded DNA containing the NF-κB consensus sequence (5′-CCTGTGCTCCGGGAATTTCCCTGGCC-3′) labeled with [Γ-32P]dATP using T4 polynucleotide kinase. The binding reaction of nuclear proteins to the probe was assessed by incubation of mixtures containing 5 μg nuclear protein, 0.5 μg poly (dI · DC) and 40,000-cpm 32P-labeled probe in the binding buffer (7.5 mm HEPES, pH 7.6, 35 mm NaCl, 1.5 mm MgCl2, 0.05 mm EDTA, 1 mm DTT, 7.5% glycerol) for 30 min at 25°C. For the competitive assay, excessive unlabeled oligonucleotides were incubated with proteins before the addition of radiolabeled probe. Protein–DNA binding complex was separated by 5% polyacrylamide gel electrophoresis and autoradiographed overnight at −80°C. Supershift assays were used to identify NF-κB subunits. One microgram of the appropriate antibody was added (Santa Cruz Biotechnology, Santa Cruz, CA) after 20 min of preincubation of nuclear extract with labeled oligonucleotide. Specificity was confirmed using excess unlabeled NF-κB oligonucleotide and mutant oligonucleotide.
Western Blot Analysis
Western blot analyses were used to measure the levels of IκB-α, ICAM-1, and iNOS in the hearts. Heart cytosolic proteins (for IκB-α and iNOS) and microsomal proteins (for ICAM-1) were loaded and separated on 7.5–10% SDS-PAGE, followed by transblotting to an ImmunBlot PVDF membrane (Bio-Rad, Hercules, CA). The membrane was subsequently probed with primary IκBα, ICAM-1, and iNOS antibodies (Santa Cruz Biotechnology) at a dilution of 1:1,000. Horseradish peroxidase–conjugated secondary antibody was added at 1:3,000 dilution. The blots were subsequently developed using an enhanced chemiluminescence detection kit (AmerSham Pharmacia Biotech, Inc., Piscataway, NJ). After exposure on autoradiography film, immunoreactive protein bands were quantified by densitometry.
Proinflammatory Cytokines
The levels of proinflammatory cytokines TNF-α and IL-1β were assessed in heart homogenates by rat enzyme-linked immunosorbent assay kits according to the manufacturer’s instructions (R&D System, Minneapolis, MN). A 1:2 dilution of samples in calibrator diluent was used for cytokine determination. Quantitation of cytokines was normalized to wet tissue weight.
Hemodynamic Measurements
To measure left ventricular pressures, a latex balloon was filled with water and connected to a pressure transducer (Medex, Dublin, CA). The balloon was inserted into the left ventricle via  the left atrial appendage through the mitral valve. The balloon volume was adjusted during the equilibration period to yield a left ventricular end-diastolic pressure of 5–10 cm H2O. Pressures were recorded using Powerlab 4/20 hardware with an amplifier (ADInstruments, Colorado Springs, CO) and Chart for Windows version 4.0.4 software (ADInstruments). Left ventricular developed pressure was used as the indication of left ventricular function.
CK Analysis
The runoff from the coronary sinus was collected for the first 10 min of reperfusion. This was placed in aliquots and stored at −80°C until analysis. The amount of creatine kinase (CK) was determined using a CK-10 kit (Sigma Diagnostics, St. Louis, MO) and a Shimadzu UV-VIS recording photospectrometer (Shimadzu, Columbia, MD). Units are expressed as units per gram of dry weight. 10 
Determination of Infarct Size
At the end of reperfusion, six hearts from each group were quickly taken down from the Langendorff apparatus and sliced into 2 mm in cross sections. The sections were immersed in 2% 2,3,5-triphenyltetrazolium chloride staining solution and placed in a 37°C incubator for 20 min. Noninfarcted myocardium stains a bright red that is caused by reduction of 2,3,5-triphenyltetrazolium chloride by dehydrogenases present in viable tissue. 11 After 20 min, slices were scanned into a computer using Adobe Photoshop 5.0LE software (Adobe, San Jose, CA). Standard computer planometric analysis, using NIH image 1.62 (public domain), was used to determine infarct area. Because the entire ventricles were at risk from global ischemia, infarct size was expressed by dividing the necrotic area by the total slice area to obtain the percent necrosis.
Analysis of variance and Student two-tailed, unpaired t  test were used to determine the differences between groups. Data are presented as mean ± SEM. Statistical significance was set at P  < 0.05.
Results
NF-κB Activation in Myocardial IR
The effect of myocardial IR and APC on the activation of NF-κB was examined by electrophoretic mobility shift assay. Compared with control, NF-κB–DNA binding activity was significantly increased at the end of reperfusion in the IR group (fig. 1A). Supershift assays showed that both p65 and p50 subunits were involved in the activation (fig. 1B). APC significantly attenuated NF-κB activation during reperfusion. The cytosolic level of IκB-α, the major NF-κB inhibitor, was also detected by Western blot analysis. As shown in figure 2, the IκB-α level was markedly decreased in the IR group compared with the control group (P  < 0.05), whereas in the APC + IR group, the IκB-α level was similar to that of the control group.
Fig. 1. Nuclear factor (NF) κB activation in rat hearts at the end of reperfusion (n = 3/group). (A  ) Electrophoretic mobility shift assay was performed to determine NF-κB–DNA binding activity. The last lane  shows the competition assay with ×100 excess molar of unlabeled oligonucleotide. (B  ) Specificity of the NF-κB–DNA complex was confirmed by supershift assay. Lanes 1  and 2  show the supershift assay using antibodies of p65 (lane 1  ) and p50 (lane 2  ). Lane 3  shows electrophoretic mobility shift assay after reperfusion. Lanes 4  and 5  show the competition assay with ×100 excess molar of activator protein 1 oligonucleotide (lane 4  ) and unlabeled NF-κB oligonucleotide (lane 5  ). The open arrow  indicates a supershift band of p50, and the closed arrow  indicates a supershift band of p65. APC = volatile anesthetic preconditioning; CTRL = control; I/R = ischemia–reperfusion.
Fig. 1. Nuclear factor (NF) κB activation in rat hearts at the end of reperfusion (n = 3/group). (A 
	) Electrophoretic mobility shift assay was performed to determine NF-κB–DNA binding activity. The last lane 
	shows the competition assay with ×100 excess molar of unlabeled oligonucleotide. (B 
	) Specificity of the NF-κB–DNA complex was confirmed by supershift assay. Lanes 1 
	and 2 
	show the supershift assay using antibodies of p65 (lane 1 
	) and p50 (lane 2 
	). Lane 3 
	shows electrophoretic mobility shift assay after reperfusion. Lanes 4 
	and 5 
	show the competition assay with ×100 excess molar of activator protein 1 oligonucleotide (lane 4 
	) and unlabeled NF-κB oligonucleotide (lane 5 
	). The open arrow 
	indicates a supershift band of p50, and the closed arrow 
	indicates a supershift band of p65. APC = volatile anesthetic preconditioning; CTRL = control; I/R = ischemia–reperfusion.
Fig. 1. Nuclear factor (NF) κB activation in rat hearts at the end of reperfusion (n = 3/group). (A  ) Electrophoretic mobility shift assay was performed to determine NF-κB–DNA binding activity. The last lane  shows the competition assay with ×100 excess molar of unlabeled oligonucleotide. (B  ) Specificity of the NF-κB–DNA complex was confirmed by supershift assay. Lanes 1  and 2  show the supershift assay using antibodies of p65 (lane 1  ) and p50 (lane 2  ). Lane 3  shows electrophoretic mobility shift assay after reperfusion. Lanes 4  and 5  show the competition assay with ×100 excess molar of activator protein 1 oligonucleotide (lane 4  ) and unlabeled NF-κB oligonucleotide (lane 5  ). The open arrow  indicates a supershift band of p50, and the closed arrow  indicates a supershift band of p65. APC = volatile anesthetic preconditioning; CTRL = control; I/R = ischemia–reperfusion.
×
Fig. 2. Western blot analysis of the IκB-α protein levels in the cytoplasm of rat hearts. (Top  ) Autoradiograms highlighting IκB-α protein levels. (Bottom  ) Quantitative data indicating the relative density of IκB-α protein levels. Data are presented as mean ± SEM; n = 3/group. *P  < 0.05 versus  control (CTRL). APC = volatile anesthetic preconditioning; I/R = ischemia–reperfusion.
Fig. 2. Western blot analysis of the IκB-α protein levels in the cytoplasm of rat hearts. (Top 
	) Autoradiograms highlighting IκB-α protein levels. (Bottom 
	) Quantitative data indicating the relative density of IκB-α protein levels. Data are presented as mean ± SEM; n = 3/group. *P 
	< 0.05 versus 
	control (CTRL). APC = volatile anesthetic preconditioning; I/R = ischemia–reperfusion.
Fig. 2. Western blot analysis of the IκB-α protein levels in the cytoplasm of rat hearts. (Top  ) Autoradiograms highlighting IκB-α protein levels. (Bottom  ) Quantitative data indicating the relative density of IκB-α protein levels. Data are presented as mean ± SEM; n = 3/group. *P  < 0.05 versus  control (CTRL). APC = volatile anesthetic preconditioning; I/R = ischemia–reperfusion.
×
Expression of Myocardial Cytokines
To investigate whether APC-induced suppression of NF-κB was associated with reduced inflammatory cytokine expression, the levels of myocardial TNF-α and IL-1β were measured. The results show that myocardial TNF-α was greatly increased at the end of reperfusion in IR group compared with the control group (P  < 0.01). APC significantly decreased the production of TNF-α (P  < 0.05;fig. 3A). IR also significantly increased the IL-1β level, and it, too, was attenuated by APC (P  < 0.01;fig. 3B).
Fig. 3. Effect of volatile anesthetic preconditioning (APC) with sevoflurane on the myocardial levels of tumor necrosis factor (TNF) α (A  ) and interleukin (IL) 1β (B  ) measured by enzyme-linked immunosorbent assay. Data are presented as mean ± SEM; n = 3/group. **P  < 0.01 versus  control (CTRL). ΔP  < 0.05 versus  ischemia–reperfusion (I/R). ΔΔP  < 0.01 versus  I/R.
Fig. 3. Effect of volatile anesthetic preconditioning (APC) with sevoflurane on the myocardial levels of tumor necrosis factor (TNF) α (A 
	) and interleukin (IL) 1β (B 
	) measured by enzyme-linked immunosorbent assay. Data are presented as mean ± SEM; n = 3/group. **P 
	< 0.01 versus 
	control (CTRL). ΔP 
	< 0.05 versus 
	ischemia–reperfusion (I/R). ΔΔP 
	< 0.01 versus 
	I/R.
Fig. 3. Effect of volatile anesthetic preconditioning (APC) with sevoflurane on the myocardial levels of tumor necrosis factor (TNF) α (A  ) and interleukin (IL) 1β (B  ) measured by enzyme-linked immunosorbent assay. Data are presented as mean ± SEM; n = 3/group. **P  < 0.01 versus  control (CTRL). ΔP  < 0.05 versus  ischemia–reperfusion (I/R). ΔΔP  < 0.01 versus  I/R.
×
Expression of ICAM-1 and iNOS
Compared with the control group, the expression of ICAM-1 protein in rat myocardium of the IR group was significantly increased as determined by Western blot (P  < 0.05). APC markedly decreased ICAM-1 protein expression (P  < 0.05;fig. 4A). The level of myocardial iNOS in the IR group was also increased. APC significantly decreased the expression of iNOS compared with that of the IR group (P  < 0.05), although it remained higher than that of the control group (P  < 0.05;fig. 4B).
Fig. 4. Effect of volatile anesthetic preconditioning (APC) with sevoflurane on the myocardial levels of intercellular adhesion molecule (ICAM) 1 (A  ) and inducible nitric oxide synthase (iNOS) (B  ) measured by Western blot analysis. Band density is represented graphically beneath the Western blot. Data are presented as mean ± SEM; n = 3/group. *P  < 0.05 versus  control (CTRL). **P  < 0.01 versus  control. ΔP  < 0.05 versus  ischemia–reperfusion (I/R).
Fig. 4. Effect of volatile anesthetic preconditioning (APC) with sevoflurane on the myocardial levels of intercellular adhesion molecule (ICAM) 1 (A 
	) and inducible nitric oxide synthase (iNOS) (B 
	) measured by Western blot analysis. Band density is represented graphically beneath the Western blot. Data are presented as mean ± SEM; n = 3/group. *P 
	< 0.05 versus 
	control (CTRL). **P 
	< 0.01 versus 
	control. ΔP 
	< 0.05 versus 
	ischemia–reperfusion (I/R).
Fig. 4. Effect of volatile anesthetic preconditioning (APC) with sevoflurane on the myocardial levels of intercellular adhesion molecule (ICAM) 1 (A  ) and inducible nitric oxide synthase (iNOS) (B  ) measured by Western blot analysis. Band density is represented graphically beneath the Western blot. Data are presented as mean ± SEM; n = 3/group. *P  < 0.05 versus  control (CTRL). **P  < 0.01 versus  control. ΔP  < 0.05 versus  ischemia–reperfusion (I/R).
×
Myocardial CK Releases, Infarct Size, and Function
The result also demonstrated that APC improved myocardial functional recovery during reperfusion. At the end of 60 min of reperfusion, left ventricular developed pressure recovered to 40.1 ± 8.3% of baseline in the APC + IR group versus  14.4 ± 2.7% in the IR group, compared with 97.5 ± 7.4 in the control group (fig. 5). CK release (units per gram dry weight) was significantly reduced by pretreatment with sevoflurane (24.63 ± 8.08 vs.  312.14 ± 28.57). CK released in control group was 2.37 ± 0.55 (fig. 6). The infarct size, expressed as percent necrotic area, was also reduced by APC (14.2 ± 2.7% in the APC + IR group vs.  30.90 ± 2.4% in the IR group;fig. 7), and there was no necrosis detected in the control hearts.
Fig. 5. Left ventricular developed pressure (LVDP) in the control (▴), ischemia–reperfusion (I/R; □), and volatile anesthetic preconditioning (APC + I/R; ▪) groups during reperfusion. This result shows a better recovery of LVDP in the APC + I/R group than in the I/R group. It also shows that there is no significant change in the control group. Data are presented as mean ± SEM; n = 6/group. *P  < 0.05 versus  I/R.
Fig. 5. Left ventricular developed pressure (LVDP) in the control (▴), ischemia–reperfusion (I/R; □), and volatile anesthetic preconditioning (APC + I/R; ▪) groups during reperfusion. This result shows a better recovery of LVDP in the APC + I/R group than in the I/R group. It also shows that there is no significant change in the control group. Data are presented as mean ± SEM; n = 6/group. *P 
	< 0.05 versus 
	I/R.
Fig. 5. Left ventricular developed pressure (LVDP) in the control (▴), ischemia–reperfusion (I/R; □), and volatile anesthetic preconditioning (APC + I/R; ▪) groups during reperfusion. This result shows a better recovery of LVDP in the APC + I/R group than in the I/R group. It also shows that there is no significant change in the control group. Data are presented as mean ± SEM; n = 6/group. *P  < 0.05 versus  I/R.
×
Fig. 6. Results of myocardial creatine kinase (CK) releases in the control (CTRL), ischemia–reperfusion (I/R), and volatile anesthetic preconditioning (APC) + I/R groups. CK is an indicator for myocardial injury. The CK release is much higher in the I/R group than in the APC + I/R group. It also shows that there is minimal CK release in the control group. Data are presented as mean ± SEM; n = 6/group. *P  < 0.05 versus  control. **P  < 0.01 versus  control. ΔΔP  < 0.01 versus  I/R.
Fig. 6. Results of myocardial creatine kinase (CK) releases in the control (CTRL), ischemia–reperfusion (I/R), and volatile anesthetic preconditioning (APC) + I/R groups. CK is an indicator for myocardial injury. The CK release is much higher in the I/R group than in the APC + I/R group. It also shows that there is minimal CK release in the control group. Data are presented as mean ± SEM; n = 6/group. *P 
	< 0.05 versus 
	control. **P 
	< 0.01 versus 
	control. ΔΔP 
	< 0.01 versus 
	I/R.
Fig. 6. Results of myocardial creatine kinase (CK) releases in the control (CTRL), ischemia–reperfusion (I/R), and volatile anesthetic preconditioning (APC) + I/R groups. CK is an indicator for myocardial injury. The CK release is much higher in the I/R group than in the APC + I/R group. It also shows that there is minimal CK release in the control group. Data are presented as mean ± SEM; n = 6/group. *P  < 0.05 versus  control. **P  < 0.01 versus  control. ΔΔP  < 0.01 versus  I/R.
×
Fig. 7. Myocardial infarct size of the ischemia–reperfusion (I/R) and volatile anesthetic preconditioning (APC) + I/R groups. The results are presented as the percent necrotic area ventricles. Data are presented as mean ± SEM; n = 6/group. ΔP  < 0.05 versus  I/R.
Fig. 7. Myocardial infarct size of the ischemia–reperfusion (I/R) and volatile anesthetic preconditioning (APC) + I/R groups. The results are presented as the percent necrotic area ventricles. Data are presented as mean ± SEM; n = 6/group. ΔP 
	< 0.05 versus 
	I/R.
Fig. 7. Myocardial infarct size of the ischemia–reperfusion (I/R) and volatile anesthetic preconditioning (APC) + I/R groups. The results are presented as the percent necrotic area ventricles. Data are presented as mean ± SEM; n = 6/group. ΔP  < 0.05 versus  I/R.
×
Discussion
The benefits of APC have been shown by improvements in myocardial functional recovery and reduced infarct size after global ischemia. 12,13 Since the first description of a protective effect of APC against myocardial IR injury, 2 numerous studies have attempted to characterize the mechanisms responsible for the response. These studies have implicated sarcolemmal and mitochondrial adenosine triphosphate–sensitive potassium channels, protein kinase C, mitochondrial Ca, intracellular pH, and ROS, 14–16 but the precise mechanism responsible for APC remains undefined.
Nuclear factor κB has been shown to play an important role in many important physiologic and pathophysiologic processes, including myocardial IR injury and IPC. 17–19 It has been shown that NF-κB is activated during IR. NF-κB is a ubiquitous inducible transcription factor that regulates the expression of numerous cellular genes, particularly those involved in the inflammatory response, which is activated during IR. More than 150 NF-κB target genes have been identified, including a number of inflammatory mediators, such as cytokines (e.g.  , TNF-α, IL-1), chemokines (e.g.  , IL-8), adhesion molecules (e.g.  , ICAM-1, vascular cell adhesion molecule-1, E-selectin), and proinflammatory enzymes (e.g.  , iNOS, cyclooxygenase 2). 20,21 Myocardial reperfusion injury is thought to be partially caused by postischemic inflammation resulting from NF-κB activation. 17,20,21 
In myocardial IR and IPC, ROS constitute one of the most potent stimulators of NF-κB activation. 21–23 Several studies support the hypothesis that APC causes a reduced ROS formation and sevoflurane and isoflurane cause direct ROS formation in cardiac tissue 14,24 On the other hand, the inhibition of ROS formation not only blocks NF-κB activation, but also abolishes the cardioprotective effects of IPC in both classic and delayed models. 19,25 Those results indicate that ROS formation and NF-κB activation are essential for the development of preconditioning.
During the trigger phase of APC, there is an initial increase in ROS, which turns on a cardioprotective program, and ROS release after prolonged ischemia is decreased, which is a beneficial effect of the early small ROS burst that occurred during the preconditioning stage of the experiment. It is postulated that reduced activation of NF-κB before the sustained IR injury and subsequent attenuation of its activation and further down-regulation of NF-κB–dependent inflammatory response during reperfusion all contribute to the myocardial protective effects of preconditioning. The attenuated NF-κB activation during IR in the preconditioned heart is thought to be caused by an increase of the inhibitor of NF-κB, IκB-α, which is also a transcriptional product of NF-κB during the preconditioning period. 19,21,26 That is, negative feedback on NF-κB activation is mediated by IκB-α, which itself is induced by NF-κB.
Tumor necrosis factor α and IL-1 are major proinflammatory cytokines that exhibit similar functional properties in their contribution to IR injury. The expression of these cytokines is regulated by NF-κB. Myocardial TNF-α is produced by resident cardiac macrophages, infiltrating leukocytes, and cardiomyocytes themselves. 27 The mechanisms by which TNF-α causes myocardial dysfunction include calcium dyshomeostasis, direct cytotoxicity, oxidant stress, and cell apoptosis as well as induction of other inflammatory cytokines (e.g.  , IL-1), chemokines, and adhesion molecules. IL-1 can synergistically enhance TNF-α–induced myocardial depression and cytotoxicity. 27 Previous studies have shown that IR causes an increase in cardiac TNF-α that impairs myocardial function. The latter conclusion is supported by evidence that protection provided by IPC against IR is related to inhibition of TNF-α production. 28–30 Similarly, treatment with anti–TNF-α antibody has been shown to improve myocardial recovery after IR. 31,32 Our results are consistent with other observations that IR causes a significant increase in the production of proinflammatory cytokines. IR-induced increase of TNF-α and IL-1 is suppressed by APC, which is associated with reduced activation of NF-κB.
Adhesion molecules also play an important role in the pathogenesis of myocardial IR injury. These molecules are expressed on cell surfaces of leukocytes and several other cell types, including endothelial cells and myocardial cells. Adhesion molecules cause leukocytes to adhere to the ischemic tissue, where they release toxic mediators, which results in considerable damage to adjacent tissues, and amplify tissue injury. ICAM-1 mediates the firm binding of leukocytes to endothelial cells through interactions with its integrin counterreceptors on leukocytes, such as CD11/18. This process is central to the trapping and accumulation of activated leukocytes in IR myocardium. 33 Monoclonal antibodies for ICAM-1 reduce IR-induced myocardial injury. 34,35 Mutant mice deficient in ICAM-1 are less susceptible to injury after transient IR. 36 The gene expression of ICAM-1 is thought to be under the regulation of NF-κB. Activation of NF-κB during IR results in up-regulation of ICAM-1, whereas inhibition of NF-κB suppresses ICAM-1 gene expression and reduces myocardial IR injury. 23,31,33,37 The results of this study reconfirm that the expression of ICAM-1 is increased during IR and show that APC significantly attenuates the expression during reperfusion.
The role of nitric oxide in IR remains controversial. 38,39 It has been suggested that nitric oxide has a dual role and can attenuate myocardial injury during IR as well as mediate reperfusion injury. Nitric oxide supplement or mimicry has been suggested to be protective. However, inhibition of nitric oxide synthase by the nitric oxide synthase inhibitor l-NAME has been shown to reduce myocardial infarct size during IR. 40–42 Furthermore, selective knock-down of iNOS with antisense oligodeoxynucleotides protects against ischemic injury. 43 It is thought that the cytotoxic effect of nitric oxide results from the formation of nitric oxide–derived free radical species, such as peroxynitrite. 44,45 Nitric oxide combines with superoxide to generate peroxynitrite, which then decomposes to yield cytotoxic hydroxyl radical and other radicals, which can cause myocardial injury. In addition, nitric oxide acts as a potent vasodilator. It is well documented that reestablishment of blood flow to ischemic tissues may exacerbate the myocardial injury, i.e.  , causing reperfusion-induced injury. Inhibition of nitric oxide synthase might be expected to impair recovery of coronary blood flow by inhibiting nitric oxide–mediated coronary vasodilation and thus reduce reperfusion-induced injury. These mechanisms are consistent with our observations that IR increases the expression of iNOS, whereas APC attenuates iNOS expression, which might contribute to the protective effects of APC.
Ischemia-reperfusion–induced myocardial injury develops as a result of damage to cardiac myocytes and endothelial cells. Proinflammatory cytokines, ROS, and nitrogen species produced by myocardial tissue during IR can directly cause cell damage. 24,27,42,46 Furthermore, the infiltrated leukocytes, which are recruited by complex interaction of multiple cytokines, chemokines, and adhesion molecules, release toxic substances in the ischemic area and thus augment tissue injury. 33,34 Again, these noxious mediators are NF-κB dependent. To reiterate, our results show that IR results in NF-κB activation, as evidenced by the diminished cytosolic level of IκB-α and increased NF-κB–DNA binding activity. Furthermore, both p50 and p65 subunits are involved in the activation of NF-κB. With NF-κB activation by IR, proinflammatory mediators are up-regulated, contribute to increased infarct size and CK release, and lead to myocardial dysfunction. Consistent with others’ findings, APC significantly decreases myocardial infarct size and improves cardiac function, which we believe is at least in part the result of reduced activation of NF-κB and down-regulation of proinflammatory responses.
The myocardial protective effects of APC may involve many different signaling pathways and mediators, such as protein kinase C, adenosine receptor, and adenosine triphosphate–sensitive K channels. This study only addresses phenomena related to NF-κB activation and the effects of APC that we observed during IR and the effect of APC in this specific model. Although NF-κB activation during preconditioning periods was not measured, the subsequent attenuation of NF-κB and the down-regulation of inflammatory gene expression are shown to be important mechanisms involved in the cardioprotection of APC with sevoflurane.
In conclusion, APC with sevoflurane decreases infarct size and CK release and improves function during reperfusion of isolated rat hearts exposed to global ischemia. NF-κB–DNA binding activity was significantly increased and cytosolic IκB was significantly decreased at the end of reperfusion. Both p50 and p65 subunits were involved in this response. Increased expressions of TNF-α, IL-1, ICAM-1, and iNOS were also observed at the end of reperfusion after untreated ischemia. APC attenuated NF-κB activation and subsequent expression of NF-κB–dependent inflammatory mediators. This attenuation of NF-κB activation could play an important role in the protective effect of APC during myocardial IR injury.
References
Murry CE, Jennings RB, Reimer KA: Preconditioning with ischemia: A delay in lethal cell injury in ischemic myocardium. Circulation 1986; 74: 1124–36Murry, CE Jennings, RB Reimer, KA
Kersten JR, Schmeling TJ, Pagel PS, Gross GJ, Warltier DC: Isoflurane mimics ischemic preconditioning via  activation of KATPchannels: Reduction of myocardial infarct size with an acute memory phase. A nesthesiology 1997; 87: 361–70Kersten, JR Schmeling, TJ Pagel, PS Gross, GJ Warltier, DC
Ioculano M, Squadrito F, Altavilla D, Canale P, Squadrito G, Campo GM, Saitta A, Caputi AP: Antibodies against intercellular adhesion molecule 1 protect against myocardial ischemia-reperfusion injury in rat. Eur J Pharmacol 1994; 284: 143–9Ioculano, M Squadrito, F Altavilla, D Canale, P Squadrito, G Campo, GM Saitta, A Caputi, AP
Cain BS, Harken AH, Meldrum DR: Therapeutic strategies to reduce TNF-α-mediated cardiac contractile depression following ischemia and reperfusion. J Mol Cell Cardiol 1999; 31: 931–47Cain, BS Harken, AH Meldrum, DR
Meldrum DR, Dinarello CA, Shames BD, Cleveland JC Jr, Cain BS, Banerjee A, Meng X, Harken AH: Ischemic preconditioning decreases postischemic myocardial tumor necrosis factor-α production: Potential ultimate effector mechanism of preconditioning. Circulation 1998; 98: II-214–9Meldrum, DR Dinarello, CA Shames, BD Cleveland, JC Cain, BS Banerjee, A Meng, X Harken, AH
Zandi E, Karin M: Bridging the gap: Composition, regulation, and physiological function of the IκB kinase complex. Mol Cell Biol 1999; 19: 4547–51Zandi, E Karin, M
Li C, Kao RL, Ha T, Kelley J, Browder IW, Williams DL: Early activation of IKKβ during in vivo myocardial ischemia. Am J Physiol Heart Circ Physiol 2001; 280: H1265–71Li, C Kao, RL Ha, T Kelley, J Browder, IW Williams, DL
Ghosh S, May MJ, Kopp EB: NF-κB and REL proteins: Evolutionarily conserved mediators of immune responses. Annu Rev Immunol 1998; 16: 225–60Ghosh, S May, MJ Kopp, EB
Mullenheim J, Molojavyi A, Preckel B, Thamer V, Schlack W: Thiopentone does not block ischemic preconditioning in the isolated rat heart. Can J Anesth 2001; 48: 784–9Mullenheim, J Molojavyi, A Preckel, B Thamer, V Schlack, W
Liu H, Cala PM, Anderson SE: Ischemic preconditioning: Effects on pH, Na and Ca in newborn rabbit hearts during ischemia/reperfusion. J Mol Cell Cardiol 1998; 30: 685–97Liu, H Cala, PM Anderson, SE
Lott FD, Guo P, Toombs CF: Reduction in infarct size by ischemic preconditioning persists in a chronic rat model of myocardial ischemia-reperfusion injury. Pharmacology 1996; 52: 113–8Lott, FD Guo, P Toombs, CF
Li F, Hayes JK, Wong KC, Szakacs J: Administration of sevoflurane and isoflurane prior to prolonged global ischemia improves heart function in isolated rat heart. Acta Anaesthesiol Sin 2000; 38: 113–21Li, F Hayes, JK Wong, KC Szakacs, J
An J, Varadarajan SG, Novalija E, Stowe DF: Ischemic and anesthetic preconditioning reduces cytosolic [Ca] and improves Ca responses in intact hearts. Am J Physiol 2001; 281: H1508–23An, J Varadarajan, SG Novalija, E Stowe, DF
Tanaka K, Weihrauch D, Ludwig LM, Kersten JR, Pagel PS, Warltier DC: Mitochondrial adenosine triphosphate–regulated potassium channel opening acts as a trigger for isoflurane-induced preconditioning by generating reactive oxygen species. A nesthesiology 2003; 98: 935–43Tanaka, K Weihrauch, D Ludwig, LM Kersten, JR Pagel, PS Warltier, DC
Nakae Y, Kwok W-M,, K, Bosnjak J, Jiang MT: Isoflurane activates rat mitochondrial ATP-sensitive K+ channels reconstituted in lipid bilayers. Am J Physiol Heart Circ Physiol 2003; 284: H1865–71Nakae, Y Kwok, W-M Bosnjak, J Jiang, MT
Stadnicka A, Bosnjak ZJ: Isoflurane decreases ATP sensitivity of guinea pig cardiac sarcolemmal KATPchannel at reduced intracellular pH. A nesthesiology 2003; 98: 396–403Stadnicka, A Bosnjak, ZJ
Valen G, Paulsson G, Vaage J: Induction of inflammatory mediators during reperfusion of the human heart. Ann Thorac Surg 2001; 71: 226–32Valen, G Paulsson, G Vaage, J
Chandrasekar B, Freeman GL: Induction of nuclear factor κB and activation protein-1 in postischemic myocardium. FEBS Lett 1997; 401: 30–4Chandrasekar, B Freeman, GL
Morgan EN, Boyle EM, Yun W, Griscavage-Ennis JM, Farr AL, Canty TG Jr, Pohlman TH, Verrier ED: An essential role for NF-κB in the cardioadaptive response to ischemia. Ann Thorac Surg 1999; 68: 377–82Morgan, EN Boyle, EM Yun, W Griscavage-Ennis, JM Farr, AL Canty, TG Pohlman, TH Verrier, ED
Pahl HL: Activators and target genes of Rel/NF-κB transcription factors. Oncogene 1999; 18: 6853–66Pahl, HL
Valen G, Zhong-qun Y, Hansson GK: Nuclear factor kappa-B and the heart. J Am Coll Cardiol 2001; 38: 307–14Valen, G Zhong-qun, Y Hansson, GK
Li N, Karin M: Is NF-κB the sensor of oxidative stress? FASEB J 1999; 13: 1137–43Li, N Karin, M
Fan H, Sun B, Gu Q, Lafond-Walker A, Cao S, Becker LC: Oxygen radicals trigger activation of NF-κB and AP-1 and upregulation of ICAM-1 in reperfused canine heart. Am J Physiol Heart Circ Physiol 2002; 282: H1778–86Fan, H Sun, B Gu, Q Lafond-Walker, A Cao, S Becker, LC
Novalija E, Varadarajan SG, Camara AKS, An J, Chen Q, Riess ML, Hogg N, Stowe DF: Anesthetic preconditioning: Triggering role of reactive oxygen and nitrogen species in isolated hearts. Am J Physiol Heart Circ Physiol 2002; 283: H44–52Novalija, E Varadarajan, SG Camara, AKS An, J Chen, Q Riess, ML Hogg, N Stowe, DF
Xuan Y-T, Tang X-L, Banerjee S, Takano H, Li R, Han H, Qiu Y, Li J, Bolli R: Nuclear factor-κB plays an essential role in the late phase of ischemic preconditioning in conscious rabbits. Circ Res 1999; 84: 1095–109Xuan, Y-T Tang, X-L Banerjee, S Takano, H Li, R Han, H Qiu, Y Li, J Bolli, R
Tähepôld P, Vaage J, Starkopf J, Valen G: Hyperoxia elicits myocardial protection through a nuclear factor κB-dependent mechanism in the rat heart. J Thorac Cardiovasc Surg 2003; 125: 650–60Tähepôld, P Vaage, J Starkopf, J Valen, G
Meldrum DR: Tumor necrosis factor in the heart. Am J Physiol 1998; 274: R577–95Meldrum, DR
Belosjorow S, Schulz R, Dorge H, Schade FU, Heusch G: Endotoxin and ischemic preconditioning: TNF-α concentration and myocardial infarct development in rabbits. Am J Physiol 1999; 277: H2470–5Belosjorow, S Schulz, R Dorge, H Schade, FU Heusch, G
Peng J, Xiao J, Ye F, Deng HW, Li YJ: Inhibition of cardiac tumor necrosis factor-α production by calcitonin gene-related peptide-mediated ischemic preconditioning in isolated rat hearts. Eur J Pharmacol 2000; 407: 303–8Peng, J Xiao, J Ye, F Deng, HW Li, YJ
Meldrum DR, Cleveland JC Jr, Cain BS, Meng X, Harken AH: Increased myocardial tumor necrosis factor-α in a crystalloid-perfused model of cardiac ischemia-reperfusion injury. Ann Thorac Surg 1998; 65: 439–43Meldrum, DR Cleveland, JC Cain, BS Meng, X Harken, AH
Kupatt C, Habazettl M, Goedecke A, Wolf DA, Zahler S, Boekstegers P, Kelly RA, Becker BF: Tumor necrosis factor-α contributes to ischemia- and reperfusion-induced endothelial activation in isolated hearts. Circ Res 1999; 84: 392–400Kupatt, C Habazettl, M Goedecke, A Wolf, DA Zahler, S Boekstegers, P Kelly, RA Becker, BF
Gurevitch J, Frolkis I, Yuhas Y, Lifschitz-Mercer B, Berger E, Paz Y, Matsa M, Kramer A, Mohr R: Anti-tumor necrosis factor-alpha improves myocardial recovery after ischemia and reperfusion. J Am Coll Cardiol 1997; 30: 1554–61Gurevitch, J Frolkis, I Yuhas, Y Lifschitz-Mercer, B Berger, E Paz, Y Matsa, M Kramer, A Mohr, R
Squadrito F, Altavilla D, Squadrito G, Saitta A, Deodato B, Arlotta M, Minutoli L, Quartarone C, Ferlito M, Caputi AP: Tacrolimus limits polymorphonuclear leukocyte accumulation and protects against myocardial ischemia-reperfusion injury. J Mol Cell Cardiol 2000; 32: 429–40Squadrito, F Altavilla, D Squadrito, G Saitta, A Deodato, B Arlotta, M Minutoli, L Quartarone, C Ferlito, M Caputi, AP
Hartman JC, Anderson DC, Wiltse AL, Lane CL, Rosenbloom CL, Manning AM, Humphrey WR, Wall TM, Shebuski RJ: Protection of ischemic/reperfused canine myocardium by CL 18/6, a monoclonal antibody to adhesion molecule ICAM-1. Cardiovasc Res 1995; 30: 47–54Hartman, JC Anderson, DC Wiltse, AL Lane, CL Rosenbloom, CL Manning, AM Humphrey, WR Wall, TM Shebuski, RJ
Yamazaki T, Yoshinori S, Tamatan T, Miyasaka M, Yagita H, Okumura H, Nagai R, Yazaki Y: Expression of intercellular adhesion molecule-1 in rat heart with ischemia/reperfusion and limitation of infarct size by treatment with antibodies against cell adhesion molecules. Am J Pathol 1993; 143: 410–8Yamazaki, T Yoshinori, S Tamatan, T Miyasaka, M Yagita, H Okumura, H Nagai, R Yazaki, Y
Soriano SG, Lipton SA, Wang YF, Xiao M, Springer TA, Gutierrez-Ramos JC, Hickey PR: Intercellular adhesion molecule-1-deficient mice are less susceptible to cerebral ischemia-reperfusion injury. Ann Neurol 1996; 39: 618–24Soriano, SG Lipton, SA Wang, YF Xiao, M Springer, TA Gutierrez-Ramos, JC Hickey, PR
Altavilla D, Deodato B, Campo GM, Arlotta M, Miano M, Squadrito G, Saitta A, Cucinotta D, Ceccarelli S, Ferlito M, Tringali M, Minutoli L, Caputi AP, Squadrito F: IRFI 042, a novel dual vitamin E-like antioxidant, inhibits activation of nuclear factor-κB and reduces the inflammatory response in myocardial ischemia-reperfusion injury. Cardiovasc Res 2000; 47: 515–28Altavilla, D Deodato, B Campo, GM Arlotta, M Miano, M Squadrito, G Saitta, A Cucinotta, D Ceccarelli, S Ferlito, M Tringali, M Minutoli, L Caputi, AP Squadrito, F
Curtis MJ, Pabla R: Nitric oxide supplement or synthesis block: Which is the better approach to treatment of heart disease? Trends Pharmacol Sci 1997; 18: 239–44Curtis, MJ Pabla, R
Rakhit RD, Edwards RJ, Marber MS: Nitric oxide, nitrates and ischemic preconditioning. Cardiovasc Res 1999; 43: 621–7Rakhit, RD Edwards, RJ Marber, MS
du Toit EF, McCarthy J, Miyashiro J, Opie LH, Brunner F: Effect of nitrovasodilators and inhibitors of nitric oxide synthase on ischemic and reperfusion function of rat isolated hearts. Br J Pharmacol 1998; 123: 1159–67du Toit, EF McCarthy, J Miyashiro, J Opie, LH Brunner, F
Schulz R, Wambolt R: Inhibition of nitric oxide synthesis protects the isolated working rabbit heart from ischemia-reperfusion injury. Cardiovasc Res 1995; 30: 432–9Schulz, R Wambolt, R
Wang P, Zweier JL: Measurement of nitric oxide and peroxynitrite generation in the postischemic heart: Evidence for peroxynitrite-mediated reperfusion injury. J Biol Chem 1996; 271: 29223–30Wang, P Zweier, JL
Noiri E, Peresleni T, Miller F, Goligorsky MS: In vivo targeting of inducible NO synthase with oligodeoxynucleotides protects rat kidney against ischemia. J Clin Invest 1996; 97: 2377–83Noiri, E Peresleni, T Miller, F Goligorsky, MS
Yasmin W, Strynadka KD, Schulz R: Generation of peroxynitrite contributes to ischemia-reperfusion injury in isolated rat hearts. Cardiovasc Res 1997; 33: 422–32Yasmin, W Strynadka, KD Schulz, R
Akiyama K, Suzuki H, Grant P, Bing RJ: Oxidation products of nitric oxide, NO2and NO3, in the plasma after experimental myocardial infarction. J Mol Cell Cardiol 1997; 29: 1–9Akiyama, K Suzuki, H Grant, P Bing, RJ
Pulkki KJ: Cytokines and cardiomyocyte death. Ann Med 1997; 29: 339–43Pulkki, KJ
Fig. 1. Nuclear factor (NF) κB activation in rat hearts at the end of reperfusion (n = 3/group). (A  ) Electrophoretic mobility shift assay was performed to determine NF-κB–DNA binding activity. The last lane  shows the competition assay with ×100 excess molar of unlabeled oligonucleotide. (B  ) Specificity of the NF-κB–DNA complex was confirmed by supershift assay. Lanes 1  and 2  show the supershift assay using antibodies of p65 (lane 1  ) and p50 (lane 2  ). Lane 3  shows electrophoretic mobility shift assay after reperfusion. Lanes 4  and 5  show the competition assay with ×100 excess molar of activator protein 1 oligonucleotide (lane 4  ) and unlabeled NF-κB oligonucleotide (lane 5  ). The open arrow  indicates a supershift band of p50, and the closed arrow  indicates a supershift band of p65. APC = volatile anesthetic preconditioning; CTRL = control; I/R = ischemia–reperfusion.
Fig. 1. Nuclear factor (NF) κB activation in rat hearts at the end of reperfusion (n = 3/group). (A 
	) Electrophoretic mobility shift assay was performed to determine NF-κB–DNA binding activity. The last lane 
	shows the competition assay with ×100 excess molar of unlabeled oligonucleotide. (B 
	) Specificity of the NF-κB–DNA complex was confirmed by supershift assay. Lanes 1 
	and 2 
	show the supershift assay using antibodies of p65 (lane 1 
	) and p50 (lane 2 
	). Lane 3 
	shows electrophoretic mobility shift assay after reperfusion. Lanes 4 
	and 5 
	show the competition assay with ×100 excess molar of activator protein 1 oligonucleotide (lane 4 
	) and unlabeled NF-κB oligonucleotide (lane 5 
	). The open arrow 
	indicates a supershift band of p50, and the closed arrow 
	indicates a supershift band of p65. APC = volatile anesthetic preconditioning; CTRL = control; I/R = ischemia–reperfusion.
Fig. 1. Nuclear factor (NF) κB activation in rat hearts at the end of reperfusion (n = 3/group). (A  ) Electrophoretic mobility shift assay was performed to determine NF-κB–DNA binding activity. The last lane  shows the competition assay with ×100 excess molar of unlabeled oligonucleotide. (B  ) Specificity of the NF-κB–DNA complex was confirmed by supershift assay. Lanes 1  and 2  show the supershift assay using antibodies of p65 (lane 1  ) and p50 (lane 2  ). Lane 3  shows electrophoretic mobility shift assay after reperfusion. Lanes 4  and 5  show the competition assay with ×100 excess molar of activator protein 1 oligonucleotide (lane 4  ) and unlabeled NF-κB oligonucleotide (lane 5  ). The open arrow  indicates a supershift band of p50, and the closed arrow  indicates a supershift band of p65. APC = volatile anesthetic preconditioning; CTRL = control; I/R = ischemia–reperfusion.
×
Fig. 2. Western blot analysis of the IκB-α protein levels in the cytoplasm of rat hearts. (Top  ) Autoradiograms highlighting IκB-α protein levels. (Bottom  ) Quantitative data indicating the relative density of IκB-α protein levels. Data are presented as mean ± SEM; n = 3/group. *P  < 0.05 versus  control (CTRL). APC = volatile anesthetic preconditioning; I/R = ischemia–reperfusion.
Fig. 2. Western blot analysis of the IκB-α protein levels in the cytoplasm of rat hearts. (Top 
	) Autoradiograms highlighting IκB-α protein levels. (Bottom 
	) Quantitative data indicating the relative density of IκB-α protein levels. Data are presented as mean ± SEM; n = 3/group. *P 
	< 0.05 versus 
	control (CTRL). APC = volatile anesthetic preconditioning; I/R = ischemia–reperfusion.
Fig. 2. Western blot analysis of the IκB-α protein levels in the cytoplasm of rat hearts. (Top  ) Autoradiograms highlighting IκB-α protein levels. (Bottom  ) Quantitative data indicating the relative density of IκB-α protein levels. Data are presented as mean ± SEM; n = 3/group. *P  < 0.05 versus  control (CTRL). APC = volatile anesthetic preconditioning; I/R = ischemia–reperfusion.
×
Fig. 3. Effect of volatile anesthetic preconditioning (APC) with sevoflurane on the myocardial levels of tumor necrosis factor (TNF) α (A  ) and interleukin (IL) 1β (B  ) measured by enzyme-linked immunosorbent assay. Data are presented as mean ± SEM; n = 3/group. **P  < 0.01 versus  control (CTRL). ΔP  < 0.05 versus  ischemia–reperfusion (I/R). ΔΔP  < 0.01 versus  I/R.
Fig. 3. Effect of volatile anesthetic preconditioning (APC) with sevoflurane on the myocardial levels of tumor necrosis factor (TNF) α (A 
	) and interleukin (IL) 1β (B 
	) measured by enzyme-linked immunosorbent assay. Data are presented as mean ± SEM; n = 3/group. **P 
	< 0.01 versus 
	control (CTRL). ΔP 
	< 0.05 versus 
	ischemia–reperfusion (I/R). ΔΔP 
	< 0.01 versus 
	I/R.
Fig. 3. Effect of volatile anesthetic preconditioning (APC) with sevoflurane on the myocardial levels of tumor necrosis factor (TNF) α (A  ) and interleukin (IL) 1β (B  ) measured by enzyme-linked immunosorbent assay. Data are presented as mean ± SEM; n = 3/group. **P  < 0.01 versus  control (CTRL). ΔP  < 0.05 versus  ischemia–reperfusion (I/R). ΔΔP  < 0.01 versus  I/R.
×
Fig. 4. Effect of volatile anesthetic preconditioning (APC) with sevoflurane on the myocardial levels of intercellular adhesion molecule (ICAM) 1 (A  ) and inducible nitric oxide synthase (iNOS) (B  ) measured by Western blot analysis. Band density is represented graphically beneath the Western blot. Data are presented as mean ± SEM; n = 3/group. *P  < 0.05 versus  control (CTRL). **P  < 0.01 versus  control. ΔP  < 0.05 versus  ischemia–reperfusion (I/R).
Fig. 4. Effect of volatile anesthetic preconditioning (APC) with sevoflurane on the myocardial levels of intercellular adhesion molecule (ICAM) 1 (A 
	) and inducible nitric oxide synthase (iNOS) (B 
	) measured by Western blot analysis. Band density is represented graphically beneath the Western blot. Data are presented as mean ± SEM; n = 3/group. *P 
	< 0.05 versus 
	control (CTRL). **P 
	< 0.01 versus 
	control. ΔP 
	< 0.05 versus 
	ischemia–reperfusion (I/R).
Fig. 4. Effect of volatile anesthetic preconditioning (APC) with sevoflurane on the myocardial levels of intercellular adhesion molecule (ICAM) 1 (A  ) and inducible nitric oxide synthase (iNOS) (B  ) measured by Western blot analysis. Band density is represented graphically beneath the Western blot. Data are presented as mean ± SEM; n = 3/group. *P  < 0.05 versus  control (CTRL). **P  < 0.01 versus  control. ΔP  < 0.05 versus  ischemia–reperfusion (I/R).
×
Fig. 5. Left ventricular developed pressure (LVDP) in the control (▴), ischemia–reperfusion (I/R; □), and volatile anesthetic preconditioning (APC + I/R; ▪) groups during reperfusion. This result shows a better recovery of LVDP in the APC + I/R group than in the I/R group. It also shows that there is no significant change in the control group. Data are presented as mean ± SEM; n = 6/group. *P  < 0.05 versus  I/R.
Fig. 5. Left ventricular developed pressure (LVDP) in the control (▴), ischemia–reperfusion (I/R; □), and volatile anesthetic preconditioning (APC + I/R; ▪) groups during reperfusion. This result shows a better recovery of LVDP in the APC + I/R group than in the I/R group. It also shows that there is no significant change in the control group. Data are presented as mean ± SEM; n = 6/group. *P 
	< 0.05 versus 
	I/R.
Fig. 5. Left ventricular developed pressure (LVDP) in the control (▴), ischemia–reperfusion (I/R; □), and volatile anesthetic preconditioning (APC + I/R; ▪) groups during reperfusion. This result shows a better recovery of LVDP in the APC + I/R group than in the I/R group. It also shows that there is no significant change in the control group. Data are presented as mean ± SEM; n = 6/group. *P  < 0.05 versus  I/R.
×
Fig. 6. Results of myocardial creatine kinase (CK) releases in the control (CTRL), ischemia–reperfusion (I/R), and volatile anesthetic preconditioning (APC) + I/R groups. CK is an indicator for myocardial injury. The CK release is much higher in the I/R group than in the APC + I/R group. It also shows that there is minimal CK release in the control group. Data are presented as mean ± SEM; n = 6/group. *P  < 0.05 versus  control. **P  < 0.01 versus  control. ΔΔP  < 0.01 versus  I/R.
Fig. 6. Results of myocardial creatine kinase (CK) releases in the control (CTRL), ischemia–reperfusion (I/R), and volatile anesthetic preconditioning (APC) + I/R groups. CK is an indicator for myocardial injury. The CK release is much higher in the I/R group than in the APC + I/R group. It also shows that there is minimal CK release in the control group. Data are presented as mean ± SEM; n = 6/group. *P 
	< 0.05 versus 
	control. **P 
	< 0.01 versus 
	control. ΔΔP 
	< 0.01 versus 
	I/R.
Fig. 6. Results of myocardial creatine kinase (CK) releases in the control (CTRL), ischemia–reperfusion (I/R), and volatile anesthetic preconditioning (APC) + I/R groups. CK is an indicator for myocardial injury. The CK release is much higher in the I/R group than in the APC + I/R group. It also shows that there is minimal CK release in the control group. Data are presented as mean ± SEM; n = 6/group. *P  < 0.05 versus  control. **P  < 0.01 versus  control. ΔΔP  < 0.01 versus  I/R.
×
Fig. 7. Myocardial infarct size of the ischemia–reperfusion (I/R) and volatile anesthetic preconditioning (APC) + I/R groups. The results are presented as the percent necrotic area ventricles. Data are presented as mean ± SEM; n = 6/group. ΔP  < 0.05 versus  I/R.
Fig. 7. Myocardial infarct size of the ischemia–reperfusion (I/R) and volatile anesthetic preconditioning (APC) + I/R groups. The results are presented as the percent necrotic area ventricles. Data are presented as mean ± SEM; n = 6/group. ΔP 
	< 0.05 versus 
	I/R.
Fig. 7. Myocardial infarct size of the ischemia–reperfusion (I/R) and volatile anesthetic preconditioning (APC) + I/R groups. The results are presented as the percent necrotic area ventricles. Data are presented as mean ± SEM; n = 6/group. ΔP  < 0.05 versus  I/R.
×