Effect of sevoflurane preconditioning on function of sarcoplasmic reticulum in cardiomyocytes during ischemia-reperfusion in isolated rat hearts

Abstract

Objective To evaluate the effect of sevoflurane preconditioning on the function of sarcoplasmic reticulum in cardiomyocytes during ischemia-reperfusion (I/R) in isolated rat hearts. Methods Healthy adult male Sprague-Dawley rats, weighing 270-300 g, were anesthetized with intraperitoneal pentobarbital.Their hearts were excised and perfused in a Langendorff apparatus with K-H solution saturated with 95% O2-5% CO2 at 37 ℃.Twenty-four isolated rat hearts successfully perfused in the Langendorff apparatus were divided into 3 groups (n=8 each) using a random number table: control group (group C), I/R group and sevoflurane preconditioning group (group SP). Myocardial ischemia was induced by interrupting perfusion for 30 min followed by 120 min reperfusion.In group SP, the hearts were perfused with 2.4% sevoflurane for 10 min starting from 10 min before ischemia.Left ventricular developed pressure (LVDP) and left ventricular end-diastolic pressure (LVEDP) were recorded at 5, 10, 15, 30 and 60 min of reperfusion.Coronary effluent was collected at 10 min before reperfusion for measurement of the levels of lactate dehydrogenase (LDH) and cardiac troponin I (cTnI). Myocardial specimens were obtained at 120 min of reperfusion for examination of the pathological changes (using HE staining) and for determination of myocardial infarct size (by TTC staining), sarcoendoplasmic reticulum Ca2+ -ATPase (SERCA2a) activity (with a spectrophotometer) and expression of Bcl-2, Bax and SERCA2a (by Western blot). Results Compared with group C, LVDP was significantly decreased and LVEDP was increased at each time point, myocardial infarct size was increased, the levels of LDH and cTnI in coronary effluent were increased, the expression of Bax was up-regulated, the expression of Bcl-2 and SERCA2a was down-regulated, and the activity of SERCA2a was decreased in group I/R (P<0.01). Compared with group I/R, LVDP was significantly increased and LVEDP was decreased at each time point, myocardial infarct size was decreased, the levels of LDH and cTnI in coronary effluent were decreased, the expression of Bax was down-regulated, the expression of Bcl-2 and SERCA2a was up-regulated, the activity of SERCA2a was increased (P<0.01), and the pathological changes were significantly attenuated in group SP. Conclusion The mechanism by which sevoflurane preconditioning reduces I/R injury in isolated rat hearts may be related to improving the function of sarcoplasmic reticulum in cardiomyocytes. Key words: Anesthetics, inhalation; Ischemic preconditioning; Myocardial reperfusion injury; Sarcoplasmic reticulum