ABSTRACT
Objective To evaluate the effects of sevoflurane postconditioning on the oncosis and apoptosis in cardiomyocytes during ischemia-reperfusion (I/R) in isolated rat hearts and the role of extracellular signalregulated protein kinase 1/2 (ERK1/2) signal transduction pathway in it.Methods Seventy-two isolated rat hearts perfused in a Langendorff apparatus were randomly divided into 6 groups (n =12 each) using a random number table:sham operation group (group S),myocardial I/R group (group I/R),sevoflurane postconditioning group (group SP),PD98059 vehicle dimethyl sulfoxide (DMSO) group (group DMSO),selective ERK1/2 inhibitor PD98059 group (group PD),and sevoflurane postconditioning + PD98059 group (group SP + PD).The hearts were subjected to ischemia for 30 min followed by 2 h reperfusion in the other groups except group S.In SP,DMSO and PD groups,the hearts were perfused with K-H solution saturated with 3.0％ sevoflurane,DMSO (＜0.2％) and PD98059 (20 μmol/L),respectively,for 15 min starting from the end of ischemia until 15 min of reperfusion,and then with plain K-H solution for 105 min.In group SP+ PD,the hearts were perfused with K-H solution saturated with 3.0％ sevoflurane and PD98059 for 15 min starting from the end of ischemia until 15 min of reperfusion.Myocardial infarct size and expression of porimin and caspase-8 proteins (by Western blot) were measured at the end of reperfusion.Results Compared with S group,the myocardial infarct size was significantly increased,and the expression of porimin and caspase-8 proteins was up-regulated in the other groups (P ＜ 0.05).Compared with I/R group,the myocardial infarct size was significantly decreased,and the expression of porimin and caspase-8 proteins was down-regulated in group SP (P ＜ 0.05),and no significant changes were found in the other groups (P ＞ 0.05).Conclusion Sevoflurane postconditioning can activate ERK1/2 signal transduction pathway and inhibit the oncosis and apoptosis in cardiomyocytes,thus attenuating I/R injury in isolated rat hearts.
ABSTRACT
Objective To evaluate the effects of sevoflurane postconditioning on the expression of 70 kD aribosomalprotein S6 kinase (p70S6K) during ischemia-reperfusion (I/R) in isolated rat hearts.Methods Pathogen-free male Sprague-Dawley rats,aged 3 months,weighing 270-350 g,were used in the study.Their hearts were excised and perfused in a Langendorff apparatus with K-H solution saturated with 95 ％ O2-5 ％ CO2.Ninety isolated rat hearts with I/R injury were randomly divided into 3 groups (n =30 each):sham operation group (group S),I/R group (group I/R),and sevoflurane postconditioning group (group SP).The hearts were subjected to ischemia for 30 min followed by 2 h reperfusion.In group SP,the hearts were perfused with K-H solution saturated with 3.0％ sevoflurane for 15 min starting from the end of ischemia until 15 min of reperfusion,and then with plain K-H solution for 105 min.At 2 h of reperfusion,myocardial infarct size was measured,the percentage of myocardial infarct size was calculated,and the phosphorylated p70S6K (p-p70S6K)/total p70S6K (tp70S6K) ratio,and cytoplasm,cytochrome C,and caspase-8 expression was measured.Results Compared with group S,the percentage of myocardial infarct size and p-p70S6K/t-p70S6K ratio were significantly increased,the expression of cytochrome C,and caspase-8 was up-regulated,and the expression of cytochrome C was downregulated in I/R group.Compared with I/R group,the percentage of myocardial infarct size was significantly decreased,the ratio of p-p70S6K/t-p70S6K was increased and cytochrome C expression was up-regulated,and the expression of cytochrome C and caspase-8 was down-regulated in SP group.Conclusion Sevoflurane postconditioning can mitigate I/R injury to isolated rat hearts,and up-regulation of p-p70S6K expression,inhibition of transfer of cytochrome C from mitochondria to cytoplasm,and reduced cell apoptosis are involved in the mechanism.
ABSTRACT
Objective To evaluate the role of the mitochondrial ATP-sensitive potassium (mito-KATP)channel in sevoflurane preconditioning-induced delayed cardioprotection against ischemia-reperfusion (I/R) injury in isolated rat hearts.Methods Seventy-two adult male Sprague-Dawley rats were randomly divided into 6 groups (n =12 each):control group (group CON),I/R group,sevoflurane control group (group SEVO),sevoflurane preconditioning group (group SWO P),5-hydroxydeconoate (5-HD) + sevoflurane preconditioning group (group 5-HD+ SWOP) and 5-HD control group (group 5-HD).The rats were exposed to 33％ pure oxygen for 1 h in groups CON and I/R.The rats were exposed to 2.5％ sevoflurane for 1 h in groups SEVO and SWOP.5-HD (a mito-KATP channel inhibitor) 10 mg/kg was injected intraperitoneally 30 min before sevoflurane preconditioning in group 5-HD + SWOP.5-HD 10 mg/kg was injected intraperitoneally in group 5-HD.The hearts were immediately removed and perfused in a Langendorff apparatus.The hearts were made globally ischemic for 30 min followed by 120 min reperfusion in groups I/R,SWOP,5-HD + SWOP and 5-HD.The expression of phosphorylated protein kinase C-epsilon (p-PKC-ε) and caspase-8 was measured by Western blot immediately before ischemia (T0) and at 120 min of reperfusion (T1).The myocardial infarct volume was measured by TTC staining.Results Compared with group CON,the myocardial infarct volume was significantly increased at T1 in groups I/R,SWOP,5-HD +SWOP and 5-HD,p-PKC-ε expression was up-regulated at T0 in groups SEVO and SWOP and at T1 in groups I/R,SWOP,5-HD + SWOP and 5-HD,and caspase-8 expression was down-regulated at T1 in group SEVO (P ＜0.05).Compared with group I/R,the myocardial infarct volume was significantly decreased at T1 in groups SWOP and 5-HD + SWOP,p-PKC-ε expression was up-regulated at T0 in groups SEVO and SWOP,and caspase-8 expression was down-regulated at T1 in group SWOP (P ＜ 0.05).Compared with group SWOP,the myocardial infarct volume was significantly increased,p-PKC-ε expression was down-regulated at T0,and caspase-8 expression was up-regulated at T1 in group 5-HD + SWOP (P ＜ 0.05).Conclusion The mito-KATP channel is involved in sevoflurane preconditioning-induced delayed cardioprotection against I/R injury in isolated rat hearts through upregulation of p-PKC-ε expression before ischemia and inhibition of cell apoptosis during reperfusion.