Objective The aim of the present study was to compare the cardioprotective effects of different therapies including local, remote, pharmacological and oxidative preconditioning in ischaemia/reperfusion injury in rats.

Methodology Rats were randomly assigned into the following groups: sham-operated and myocardial ischaemia/reperfusion (40 min/10 min). Other groups were subjected to different preconditioning treatments before the operation. Two groups received oral doses of pioglitazone (10 mg/kg/day) or nicorandil (3 mg/kg/day) for 5 days. Other two groups were subjected to local or remote preconditioning by three cycles of 5 min of occlusion of either left descending coronary artery or right femoral artery followed by 5 min of reperfusion. The last two groups received either ozone (0.6 mg/kg/day in the first week followed by 1 mg/kg/day in the second week) or oxygen vehicle by rectal insufflations. Heart rate, ventricular arrhythmias and descending aortic blood flow were continuously recorded during the whole operation.

Results The arrhythmia score in all groups except ozone was reduced significantly compared to ischaemia/reperfusion group. Ventricular premature beats and bigeminy were significantly lowered in local preconditioning and pioglitazone groups. Trigeminy, salvos and ventricular tachycardia were completely abolished in local preconditioning and pioglitazone groups. Torsade de pointe was completely abolished in all treated groups except remote preconditioning. Ventricular tachycardia duration was significantly reduced in all groups compared to ischaemia/reperfusion group. Finally, descending aortic blood flow was seriously reduced during the incidence of ventricular arrhythmias which was significant in ischaemia/reperfusion group. All different preconditioning therapies show a protective effect against blood flow reduction. This was markedly observed in local preconditioning and ozone groups.

Conclusion Different preconditioning therapies exert a protective effect by reducing serious ventricular arrhythmias during myocardial ischaemia/reperfusion. This was markedly reflected in part by their blood flow preservative effects.