ISCHEMIC PRECONDITIONING REDUCES INFARCT SIZE FOLLOWING GLOBAL-ISCHEMIA IN THE MURINE MYOCARDIUM

Ischaemic preconditioning has not been demonstrated to reduce infarct size following global ischaemia in murine myocardium. Eighteen mouse h earts were isolated, perfused in the Langendorff mode, and randomised to control or preconditioning groups. Preconditioned hearts received f our periods of five minutes global ischaemia with five minutes of inte rvening reperfusion. Control hearts were perfused normally during this period. Both groups were then subjected to 30 minutes global ischaemi a followed by 30 minutes reperfusion. Infarct size, contractile recove ry and LDH leakage were assessed. Mean infarct size was reduced from 5 7 % of ventricular volume (controls) to 33 % in preconditioned hearts (P = 0.003). A small improvement in contractile recovery was also obse rved (6.3 % of baseline in controls, 15.5 % in preconditioned hearts; P = 0.004). Release of LDH did not differ significantly between groups . This study confirms for the first time that ischaemic preconditionin g can delay the onset of myocardial necrosis following global ischaemi a in the isolated mouse heart.