Differential effects of running and weight-lifting on the rat coronary arterial tree

Twenty-four postpubertal male albino rats were assigned randomly to sedentary-control (C), endurance-running (ER), and weight-lifting (WL) groups to study the effects of different chronic-exercise regimens on precapillary vascularity in the heart. The exercise routines were administered 5 d/wk. At the end of either 8 or 16 wk of treatments, half of the animals in each group were anesthetized. A 12% vinyl acetate solution was injected into the coronary arteries of each anesthetized animal at a pressure of 300-350 mmHg, through the ascending aorta. The injected hearts were removed and weighed. A 10% potassium hydroxide solution was used to digest tissues from the vinyl cast of each coronary arterial tree. No differences in absolute or relative heart weights were observed between the control and trained groups. When compared to the control group, the ER animals had heavier left and total coronary cast weights and higher total cast weight-to-heart weight ratios (P less than 0.05). Although an overall increase in precapillary vascularity of the heart was evident in the endurance-trained ER animals, none was found in the strength-trained WL group. However, the WL animals had significantly increased right coronary cast weights, and their ratios of right coronary cast weight to total cast weight also were higher than those of the control animals (P less than 0.05).