protective effect of vitamin E in stress-induced myocardial lesion in rats

ABSTRACT

The effect of vitamin E on the changes induced in the rat heart by chronic isoproterenol treatment was examined. Administration of isoproterenol [1 mg/kg] daily for 7 consecutive days has evoked significant hypertrophy in all cardiac chambers. The basal heart rate in chronically isoproterenol-treated rats was lower than in saline-treated control rats [315 +/- 9 vs 348 +/- 16 b.p.m. P < 0.05]. Also the chronotropic responses to isoproterenol graded infusion in sequential doses were significantly higher in control rats than in chronically isoproterenol-treated rats [145 +/- 23 vs 92 +/- 13 maximal increments in heart rate b.p.m., P < 0.05]. Pretreatment with vitamin E has only prevented hypertrophy in atria but did not modify the hypertrophic response in ventricles of isoproterenol-treated rats. Moreover, it ameliorated the difference in heart rate between the isoproterenol-treated and the saline-treated rats both in basal condition [306 +/- 10 vs 330 +/- 12, n.s.] and in response to graded stimulation by isoproterenol infusion [115 +/- 19 vs 117 +/- 14 maximal increments in heart rate b.p.m., n.s.]. The protective effect of antioxidant vitamin E against the reduction in chronotropy and chronotropic responses in chronically isoproterenol-treated rats, may point to the role of oxygen free radicals in mediation of these functional cardiac disturbances