Effects of actinomycin D and hypophysectomy on development of myocardial hypertrophy in the rat

Abstract

In the present study left ventricular hypertrophy was produced in 6 groups of 12 or more 150-g rats by constriction of the abdominal aorta. The inhibitory effect on the increase in muscle mass of hypophysectomy and actinomycin D in 3 dosage levels (7.7, 25, and 50 [mu]g/100 g) was studied. The results indicate in normal rats the left ventricle (LV) increases about 22% in weight within 5 days after operation; the LV of chronically hypophysectomized rats increases 16%; in rats receiving the lowest 2 dosages of actinomycin D no inhibitory effect was observed, whereas at the highest level (50 [mu]g/100 g) the LV increased only 9% in weight. Animals receiving more than 7.7 [mu]g/100 g of the drug exhibited considerable morbidity and mortality. These results indicate that hypophysectomy and actinomycin D can inhibit myocardial hypertrophy. The inhibitory effect on actinomycin D occurs only with highly toxic dosages.