Effects of digitoxin on the ultrastructural myocardial changes in the rat subjected to chronic exercise

Abstract

Female Sprague-Dawley rats were divided into 4 groups: Group A (control rats); Group B (rats receiving 0.15 mg of digitoxin per 100 g of body weight daily for 6 days of each week); Group C (swimming control rats); and Group D (swimming rats receiving digitoxin in the manner of Group B). The exercised animals swam 6 hours daily, 6 days a week until 400 to 1,500 hours of total swimming time had been reached. Electron microscopic data indicated that although the number of mitochondria increased in hearts from rats subjected to swimming, degeneration occurred in a significant proportion of the mitochondria. The swimming rats given digitoxin, unlike the untreated swimming rats, had insignificant mitochondrial damage. Therefore, mitochondrial integrity, in relation to the morphologic appearance, is apparently better preserved in the swimming rat receiving digitoxin than in the untreated swimming rat.