Role of endogenous oxytocin in cardiac ischemic preconditioning

The aim of the present study is to assess the role of endogenous oxytocin (OT) in cardioprotective effects of ischemic preconditioning (IPC) in anesthetized rat.Animals were divided into five groups: 1) ischemia-reperfusion (IR); (n=6), hearts were subjected to 25 min regional ischemia and 60 min reperfusion, 2) OT; (n=6), oxytocin was administered (0.03 μg/kg i.p) 10 min prior to ischemia, 3) IPC; (n=7), IPC was induced via a 5 min regional ischemia followed by 5 min of reperfusion before IR, 4) IPC+ATO (Atosiban); (n=6), atosiban (1.5 μg/kg i.p) was used as OT receptor selective antagonist in the beginning of IPC and 5) IR+ATO; (n=6), atosiban was injected 10 min prior to ischemia-reperfusion.In our experiment, Infarct size was decreased significantly in OT and IPC groups compared to IR (23 ± 1.5% and 19 ± 0.6% vs. 45 ± 2.9% in IR group, P0.05). Administration of atosiban in IPC+ATO group increased infarct size to 39 ± 0.9% in comparison with OT and IPC groups (P0.05). The use of OT and IPC prior to ischemia significantly declined ventricular arrhythmias severity in compared to IR group (1.2 ± 0.4 and 1 ± 0.5 respectively, vs. 4 ± 0.4 in IR group, P0.05). Blockade of OT receptor by atosiban abolished the cardiopreconditioning effects of IPC.This study shows that, in part, the cardioprotective effects of IPC can be induced by endogenous OT.