Study of ischemic and pharmacologic postconditioning on infarct size in the ischemic reperfused isolated heart

In this study, effects of ischemic postconditioning (IPC) and pharmacologic postconditioning (PPC) by using L-Carnitine (L-Car) on infarct size in the ischemic-reperfused isolated rat heart were investigated and compared.

Male rats were divided in five groups (control, IPC, and three PPC groups treated by L-Car) and were anesthetized by sodium pentobarbital (50 mg/kg-ip). Heart was removed and quickly mounted on a Langendorff apparatus and perfused by a modified Krebs-Henseleit (K/H) solution that was previously equilibrated with 95% O2–5% CO2. The hearts were subjected to 30 min regional ischemia followed by 120 min reperfusion. In the control and IPC groups, the hearts were perfused by normal K/H solution at stabilization, 30 min regional ischemia and 120 min reperfusion, while PPC groups were perfused by 0., 2.5 and 5mM of L-Car enriched K/H solution 10 min before and after reperfusion. At the end of reperfusion, infarct size was determined by triphenyltetrazolium chloride method and computerized planimetry.

Infarct size was decreased significantly in both IPC and PPC groups versus control. In control group, infarct size was 46.3±2.9 %, however, IPC reduced it to 22.6±1.5 % (p<0.001). Application of 0.5, 2.5 and 5mM of Car-enriched K/H solution 10 min before and after reperfusion in the PPC groups, reduced the infarct size from control group value to 41.8±4.0 (not significant), 28.1±2.0 (p<0.001) and 25.4±. % (p<0.001), respectively. Except the effects of 0.5 mM L-Car, there was no significant difference between IPC and PPC groups on infarct size reduction.

Considering the results, it may be concluded that IPC and PPC (by L-Car) have protective effects against cardiac I/R injuries by reduction of infarct size.