The Present work was conducted to study the cardioprotective effects
of long-term administration of two antikpertensive 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 (T Ch) Triglycerides (t G). 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 a DA) 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 significantly 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 infarct 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 .
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