Exercise training ameliorates age‐related diastolic dysfunction: the role of coronary microvascular function

Abstract

The risk for diastolic heart failure increases with advancing age. Regular physical exercise has been shown to prevent and/or ameliorate the progression of age‐related diastolic dysfunction; however, the underlying mechanisms have not been identified. We tested the hypothesis that adaptations of coronary microvascular function contribute to age‐ and exercise‐related changes in cardiac diastolic dysfunction. Young and old Fischer 344 male rats were randomly assigned into either a sedentary control group or an exercise‐trained group. Doppler analysis was used to evaluate ventricular diastolic function. Coronary arterioles were isolated from the left ventricular free wall to assess arteriolar contractile function. Vascular smooth muscle (VSM) proliferation was assessed by measuring wall:lumen ratio and by analysis of phosphohistone H3. Doppler analysis showed that age impaired cardiac diastolic function and late‐life exercise training improved diastolic function. Age impaired contractile function and induced localized VSM proliferation in coronary resistance arterioles. Exercise training reversed age‐related contractile dysfunction of coronary resistance arterioles and attenuated VSM cell proliferation. Our findings suggest that age and exercise affect cardiac function, in part, through alterations of VSM function of coronary resistance arterioles.