Effects of Long Term Exercise on Cardiac Hemodynamic and Contractility Measures in Aging Rats

Abstract

Pressure‐volume (P‐V) analysis is a robust approach for the study of in‐vivo ventricular function. In this study, we characterized P‐V alterations that occur with advanced age, with and without long‐term exercise training. Adult (24 month) male Fischer 344 x Brown Norway (FBN) rats were randomly divided into 3 groups; high intensity exercise (HI), moderate intensity exercise (MI), and sedentary (S). MI and HI animals trained at 13 m/min for 30 min/day, with the HI group at 5% incline. Animals were trained daily for 12 months until 36 months of age. Hemodynamic measurements were conducted via a P‐V catheter in the left ventricle (LV) in 36‐month old animals. As a result of the exercise training, rats in the MI group had significant increases (compared to S) in indices of contractility such as End Systolic Pressure‐ Volume relationship (ESPVR), and dP/dtmax. HI animals showed no such improvement and, in fact, had decreases in resting cardiac parameters such as stroke volume, cardiac output, stroke work, and ejection fraction, when compared to MI and S animals. End‐ Diastolic Pressure‐Volume Relationship (EDPVR) was higher in S compared to MI and HI groups. We conclude that long‐term exercise training altered cardiac function in aged hearts but that the response is dependent on exercise intensity. Supported by: NIH AG030423