PROTECTIVE EFFECT OF BISOPROLOL AND ISRADIPINE ON ACUTE MYOCARDIAL INFARCTION IN RABBITS
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The Present work was conducted to study the cardioprotective effects of long-term administration of two antihypertensive drugs namely Bisoprolol a B, adrenergic blocker, and isradipine, a dihydropyridine calcium antagonist, in male rabbits fed high cholesterol diet for two months. Their actions on the serum creatine Phosphokinase (CPK), lipid profile, (total cholesterol (TCh) Triglycerides (TG), low density lipoprotein (LDL) high density lipoprotein (HDL) ) and their actions on aorta anf the infarct size of atherosclerotic rabbits were investigated . Male rabbits were rendered atherosclerotic by feeding cholesterol in a daily dose of 100 mg/kg for 2 months. Over the same period of cholesterol feeding, rabbits were treated with either Bisoprolol (0.2 mg/kg orally) or isradipine (0.5 mg/kg/day orally) . At the end of the two months, rabbits were subjected to coronary artery ligation (LDA) for 4 hours. Three parameters were studied namely electrophysiological parameter recording S.T segment elevation using electrocardiogram, biochemical parameter recording plasma CPK before and after 4 hours of ligation of LAD and histochemical parameter (Staining heart sections with triphenyl tetrazolium (TPT) 4 hours after ligation of LAD and the infarct areas were computed) . in addition histopathological changes in aorta were studied. In this study Both Bisoprolol and isradipine decreased significantly ST segment elevation after LAD ligation compared to the atherosclerotic group. Also both drugs signcantly decreased the rise in CPK level 4 hours after ligation of LAD compared to the atherosclerotic group at the same time interval. Both of them decreased the infarct size significantly compared to the atheresclerotic group. Moreover isradipine, but not Bisoprolol improved lipid profile of astherosclerotic animals, but both drugs improved histopathological changes in aorta . From all the results of this study it can be concluded that both Bisoprolol and isradipine can be used in acute myocardial infarction to limit the Ward size. Long term administration of both drugs is effective and of great value in decreasing the incidence of myocardial infarction or decreasing its size. Since both drugs inhibited development of atherosclerosis on long-term adminstration which is a major risk factor in development of coronary heart diseases, so both drugs are efficient prophylactic agents in patients liable to atherosclerosis and coronary heart disease .