Amiodarone offsets the cardioprotective effects of ischaemic preconditioning against ischaemia/reperfusion injury.

Both ischaemic preconditioning (IPC) and amiodarone protect against myocardial ischaemia. We examined whether a combination of IPC and amiodarone demonstrated an additive protective effect in isolated rat hearts (n = 40). The controls (group I) were subjected to ischaemia/ reperfusion injury; group II was subjected to cycles of IPC prior to ischaemia/ reperfusion injury; group III was subjected to ischaemia in the presence of amiodarone (10(-10) mol/1); and group IV was subjected to IPC followed by ischaemia in the presence of amiodarone (10(-10) mol/l). Amiodarone produced the best preserved left ventricular end-systolic pressure and dP/dtmax, less developed ventricular stiffness, the shortest arrhythmia duration, and the smallest infarct size among the groups. All of the myocardial protective effects against ischaemia/reperfusion injury were diminished or abolished when IPC and amiodarone were applied sequentially.