RESUMO
An experimental model of myocardial infarction has been reproduced in rats by S.C. injection of isoproterenol [85 mg/kg] for two days. The prophylactic properties of verapamil and propranolol before and after gamma-irradiation against this model of myocardial necrosis were investigated. Pretreatment with verapamil or irradiated verapamil significantly reduced the myocardial damage, the enzymes LDH and CK leakage and the increase in plasma creatinine. However, verapamil and its irradiated form did not affect isoproterenol-induced elevation of plasma creatine, FFA as well as cardiac NE content. On the other hand, injection of propranolol or irradiated propranolol prior to isoproterenol significantly reduced the myocardial necrosis, the enzymes LDH and CK leakage and the plasma creatinine. Meanwhile, the elevated levels of plasma FFA and cardiac NE content arising from isoproterenol injection were normalized and reduced respectively by propranolol and irradiated propranolol pretreatment. The present study revealed that irradiation of verapamil and propranolol at dose level of 25 KGy did not change their prophylactic properties against isoproterenol-induced myocardial necrosis as compared to non-irradiated drugs