Effects of digitoxin on the development of cardiac hypertrophy in the rat subjected to chronic exercise

Abstract

Sixty female Sprague-Dawley rats were divided into four groups of 15 animals each: Group A, control animals; 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 animals; and Group D, rats that received digitoxin and also swam. The exercised animals swam 6 hours a day, 6 days a week until 400 to 1,500 hours of total swimming time had been reached. The parameters measured were body weight, heart weight, right and left ventricular thickness, myocardial isometric systolic tension and ventricular pressure before and during acute aortic occlusion. The presence or absence of digitoxin was not a significant source of variation in any of these parameters in either the control or the swimming rats, but the swimming factor was a significant source of variation. There was no detectable interaction between swimming and digitoxin. Therefore, it can be stated that, unlike the pathologic hypertrophy of disease, the physiologic hypertrophy produced by intermittent exercise and the increment in myocardial function concomitant to the hypertrophy are not altered by treatment with digitoxin.