ABSTRACT
Cardiac ischemic reperfusion injury is gaining importance due to rising of cardiac intervention procedures invoking transient ischemia, which requires trials of preconditioning strategies, A possible beneficial one could be the use of medical ozone, which is known to play a vital role in our well -being Therefore, the effect of small dose medical ozone on heart muscle and its possible protective effect on subsequent ischemia/ reperfusion injury was evaluated. Animals included in the present study were allocated into three groups: unconditioned control rats [group I], two months-ozonepreconditioned rats [group II], and three months-ozone-preconditioned rats [group III]. Rats were injected i.p. with small doses of ozone twice weekly. At the end of the experimental period, half the rats in each group were injected with heparin, a blood sample was taken for determination of plasma malondialdehyde [MDA] and the heart excised and used for isolated heart study. A blood sample was collected from the other half in each group for determination of serum glucose and the heart excised and sent for histological examination. Isolated heart study was carried out according to modified Langendorff technique. After recording basal cardiac activity, global ischemia was induced by stoppage of perfusion for 30 minutes followed by resumption of flow for another 30 minutes, and cardiac activity then recorded. The results revealed signifcant reduction in intrinsic inotropy of hearts isolated from unconditioned control rats after ischemia/ reperfusion [I/R], evidenced by significant decrease in tension generation per unit time [PT/t] after I/R in these rats, together with prolongation, of half relaxation time, insignificant change of intrinsic chronotropic activity and myocardial flow rate after I/R. Two months-medical ozone-preconditioning resulted in correction of the impaired intrinsic inotropy after I/R seen in unconditioned control rats, with enhancement of diastolic function. However, three months- medical-ozone preconditioning did not protect the hearts isolated from these rats from systolic dysfunction after I/R, though the diastolic function was significantly improved after I/R compared to unconditioned control rats. Serum glucose was decreased and plasma malondialdehyde was significantly increased in both the two-and three-months ozone-preconditioned rats. Histological examination of heart muscle revealed increased mitochondria! density in ozone preconditioned rats which was more marked in the two months-ozone-treated rats