Effects of Estradiol, Angiotensin-Converting Enzyme Inhibitor and Exercise Training on Exercise Capacity and Skeletal Muscle in Old Female Rats

Abstract

Physical fitness is closely related to cardiovascular health. We examined the effects of estradiol, angiotensin-converting enzyme inhibitor, exercise training, and their combination on exercise capacity as well as skeletal muscle fiber type and capillarity in old female rats. Twelve-month-old female Wistar-Kyoto rats were allocated to six groups: control (C), treatment with 17 beta-estradiol (0.025 mg/kg/dose, i.p. twice a week) (Est), perindopril (2 mg/kg/day) (Per), exercise training on a treadmill (15 m/min, 10 grade incline, 60 min/day, 5 days/week) (Exe), and combinations of a drug and exercise training (Exe+Est and Exe+Per). Following 6-month interventions, the rats were submitted to a stepwise exercise test on a treadmill. Moreover, fiber type and capillarity in both the soleus and gastrocnemius muscles were examined. Exercise capacity, capillary density, and the percentage of type I fiber significantly increased in Exe, Exe+Est, and Exe+Per compared to C. There were no significant differences in exercise capacity, capillary density, and percentage of type I fiber among C, Est, and Per. The combination of exercise training and perindopril further increased capillary density in both the soleus and gastrocnemius muscles, and the percentage of type I fiber in the gastrocnemius muscle compared to exercise training alone. We found that in old female rats, chronic treatment with estradiol or perindopril affected neither untrained exercise capacity nor exercise capacity acquired as a result of exercise training. However, we found that perindopril promotes adaptive changes of skeletal muscle in response to exercise such as increases in capillary density and the percentage of type I fiber.