Isoflurane preconditioning significantly reduced myocardial infarct size compared with control (40% vs 58%; P<0.05), an effect that was abolished by PKC and PTK inhibitors.
Isoflurane-induced preconditioning protects against myocardial ischemia-reperfusion injury in vivo through mechanisms involving PKC-delta, PKC-epsilon, and Src PTK.
Absolute Event Rate: 40% vs 58%
p-value: p=< 0.05
BACKGROUND: The authors tested the hypotheses that protein kinase C (PKC)-specific isoform translocation and Src protein tyrosine kinase (PTK) activation play important roles in isoflurane-induced preconditioning in vivo. METHODS: Rats (n = 125) instrumented for measurement of hemodynamics underwent 30 min of coronary artery occlusion followed by 2 h of reperfusion and received 0.9% saline (control); PKC inhibitors chelerythrine (5 mg/kg), rottlerin (0.3 mg/kg), or PKC-epsilonV1-2 peptide (1 mg/kg); PTK inhibitors lavendustin A (1 mg/kg) or 4-amino-5-(4-methylphenyl)-7-(t-butyl)pyrazolo3,4-dpyrimidine (PP1; 1 mg/kg); mitochondrial adenosine triphosphate-sensitive potassium channel antagonist 5-hydroxydecanote (10 mg/kg); or reactive oxygen species scavenger N-acetylcysteine (150 mg/kg) in the absence and presence of a 30-min exposure to isoflurane (1.0 minimum alveolar concentration) in separate groups. Isoflurane was discontinued 15 min before coronary occlusion (memory period). Infarct size was determined using triphenyltetrazolium staining. Immunohistochemistry and confocal microscopic imaging were performed to examine PKC translocation in separate groups of rats. RESULTS: Isoflurane significantly (P < 0.05) reduced infarct size (40 +/- 3% n = 13) as compared with control experiments (58 +/- 2% n = 12). Chelerythrine, rottlerin, PKC-epsilonV1-2 peptide, lavendustin A, PP1, 5-hydroxydecanote, and N-acetylcysteine abolished the anti-ischemic actions of isoflurane (58 +/- 2% n = 8, 50 +/- 3% n = 9, 53 +/- 2% n = 9, 59 +/- 3% n = 6, 57 +/- 3% n = 7, 60 +/- 3% n = 7, and 53 +/- 3% n = 6, respectively). Isoflurane stimulated translocation of the delta and epsilon isoforms of PKC to sarcolemmal and mitochondrial membranes, respectively. CONCLUSIONS: Protein kinase C-delta, PKC-epsilon, and Src PTK mediate isoflurane-induced preconditioning in the intact rat heart. Opening of mitochondrial adenosine triphosphate-sensitive potassium channels and generation of reactive oxygen species are upstream events of PKC activation in this signal transduction process.
Ludwig et al. (2004) studied Myocardial ischemia-reperfusion injury (n=125). Isoflurane vs. 0.9% saline (control) was evaluated on Infarct size (p=< 0.05). Isoflurane preconditioning significantly reduced myocardial infarct size compared with control (40% vs 58%; P<0.05), an effect that was abolished by PKC and PTK inhibitors.
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