Exercise Training Attenuates Age-Associated Diastolic Dysfunction in Rats

Abstract

Background — In contrast to systolic function, which is relatively well preserved with advancing age, diastolic function declines steadily after age 30. Our goal was to determine whether changes in diastolic function that occur with aging could be reversed with exercise training. Methods and Results — Adult (6-month-old) and old (24-month-old) Fischer 344/BNF1 rats were studied after either 12 weeks of treadmill training or normal sedentary cage life. Three aspects of diastolic function were studied: (1) left ventricular (LV) filling in vivo via Doppler echocardiograph, (2) LV passive compliance, and (3) the degree of ischemia-induced LV stiffening. Maximal exercise capacity was lower in the old rats (18±1 minutes to exhaustion on a standard treadmill) than in the adult rats (25±1 minutes). Training increased exercise capacity by 43% in the old rats and 46% in the adults (to 26±1 and 37±1 minutes, respectively). Echocardiographic indices of LV relaxation were significantly lower in the old rats, but with training, they increased back to the levels seen in the adults. LV stiffness measured in the isolated, perfused hearts was not affected by age or training. Also in the isolated hearts, the LV stiffened more rapidly during low-flow ischemia in the old hearts than in the adults, but training eliminated this age-associated difference in the response to ischemia. Conclusions — Our findings indicate that in rats, some age-associated changes in diastolic function are reversible and thus may not be intrinsic to aging but instead secondary to other processes, such as deconditioning.