Memory phase of the cardioprotective effect of isoflurane preconditioning on isolated rat myocardium

Abstract

Objective To investigate the memory phase of the protective effect of isoflurane preconditioning (IsoP) on rat myocardium. Methods 24 isolated SD rat hearts were divided into four groups: IR, M1, M2 and M3 groups (n=6) according to the time of washout before ischemia. After equilibration, the hearts were perfused for 20 min, 10 min and 0 min in M1, M2 and M3 groups respectively, using Langen dorff apparatus, then received two cycles IsoP and followed by 10 min, 20 min and 30 min washout respectively. All the hearts were subjected to 30 min sustained ischemia and 60 min reperfusion. LVEDP, LVDP, and-dp/ dtmax were recorded. The release of CK and LDH in the outflow and the size of survival myocardium area were measured. Results During reperfusion, the recovery of LVEDP was lower in M1, M2 and M3 groups than that in IR group (P＜0.01). LVDP in M1 and M2 groups increased (P＜0.05). The percentage of recovery of LVDPxHR in M1 and M2 groups at 30 min and 60 min of reperfusion were higher than that in IR group (P＜0.05). The release of CK in memory groups significantly decreased (P＜0.05) and the contents of LDH in M1 group was lower than other groups (P＜0.05). The percentage of survival area of myocardium in M1 and M2 groups was higher than that in IR group and M3 group (P＜0.05). Conclusion The best memory phase of the cardioprotective effect of IsoP is about 20min in isolated rat heart. Key words: Isoflurane preconditioning; Cardiopmtection; Ischemia/reperfusion injury; Memory phase