Effect of heart preservation solution containing pinacidil on mitochondrial function in isolated rat hearts

Abstract

Objective To investigate the effect of mitochondrial function in isolated rat hearts. Methods One heart preservation solution containing pinacidil on hundred and twenty pathogen-free SD rats of both sexes weighing 250-350 g were used in this study. The animals were anesthetized with intraperitoneal pentobarbital 65 mg/kg. Their hearts were immediately removed and perfused in a Langendorff apparatus. Left ventricular enddiastolic pressure was measured from a fluid-filled latex balloon inserted in the left ventricle. The isolated hearts were randomized into 5 groups （ n = 24 each） ： group I was perfused with cardioplegic solution HTK; group II with HTK containing pinacidil （a non-specific sarcKATP and mitoKATP channel opener） 0.5 mmol/L; group III with HTK containing pinacidil 0.5 mmol/L ＋ 5-HD （a selective mitoKATP channel blocker） 100 umol/L; group IV with HTK containing pinacidil 0.5 mmol/L ＋ HMR-1098 100 umol/L （a selective sarcKATP channel blocker） and group V with HTK containing pinacidil 0.5 mmol/L ＋ 5-HD 100 umol/L ＋ HMR-1098 100 umol/L. The isolated hearts were perfused with simple HTK or HTK containing pinacidil or pinacidil ＋ 5-HD and/or HMR 20 ml/kg at 10 ml/min and then removed from Langendorff apparatus and dipped into the same HTK solution for 8 h at 4℃ followed by 60 rain reperfusion. The respiratory function of mitoebondria （respiratory control rate （RCR）, the rate of oxygen consumption in state 3/state 4 and P/O） was measured at the end of equilibration （T1 ） after 8 h preservation （T2） and at the end of 60 min reperfusion （T3 ）. The CK-MB and LDH activities and cTnI expression in myocardium was detected at T2 and T3 . The ultrastructure of myocardimn was examined at T3 . Results Perfusion suspension-reperfusion （PS/R） significantly decreased mitochondfial respiratory function （RCR, P/O and rate of O2 consumption in state 3） and increased myocardial cTnI concentration and CK-MB and LDH activities at T3 compared with baseline at T1 in group I. Pinacidil significantly increased mitochondrial respiratory function （RCR, P/O and rate of O2 consumption in state 3） and decreased myocardial cTnI concentration and CK-MB and LDH activities in group II as compared with group I indicative of protective effect of pinacidil on mitochondfia against PS/R injury. The protective effect of pinacidil against PS/R injury was attenuated by 5-HD and/or HMR- 1098. The myocardial damage was slightest in group II. Conclusion Both sarcolemmal and mitochondrial KATe channel are involved in the protective effect of pinacidil against PS/R-induced myocardial damage during heart preservation. Key words: Pinacidil; Organ preservation solution ; Mitochondria, heart