Protection against ischemia-reperfusion induced oxidative stress by vitamin E treatment.

The rat heart protection offered by vitamin E against oxidative stress after ischaemia-reperfusion was studied by using a new methodological approach. Functional recovery of hearts from ischaemia-reperfusion was correlated with a traditional index of oxidative stress such as lipid peroxidation and with antioxidant capacity and susceptibility to oxidants of the tissue evaluated by enhanced chemiluminescence techniques. Rats were treated with ten daily i.m. injections of 100 mg/kg body weight of vitamin E. The functional recovery during reperfusion (20 min, following 45 min ischaemia) of Langendorff preparations from control (vehicle-injected) and vitamin E treated rats was evaluated in terms of heart rate, left ventricular developed pressure (LVDP), double product (= heart rate. LVDP) and coronary flow recovery. Vitamin E treatment significantly improved functional recovery of heart rate, LVDP, double product and coronary flow. It also increased the level of vitamin E and reduced the levels of both malondialdehyde and hydroperoxides in the heart tissue at the end of the ischaemia-reperfusion protocol. In contrast, it did not affect the antioxidant capacity and the response of heart homogenates to in vitro oxidative stress measured after ischaemia-reperfusion. These results show a protective action of vitamin E treatment against lipid peroxidation and cardiac dysfunction associated with ischaemia-reperfusion. Although the precise mechanism of this protection is not evident, our model in part suggests a role of vitamin E other than as a free radical scavenger.