Left Ventricular Pressure-Volume Relationship and Effect of Long-term Exercise in A Rat Model of Advanced Aging

ABSTRACT

BACKGROUND: Heart failure due to diastolic dysfunction rises dramatically with age. Normal aging process is also known to depress left ventricular diastolic performance. It was reported that exercise training prevented diastolic dysfunction in old men and old rats. We investigated the diastolic function after long-term exercise training in old rats using the Millar Pressure-Volume conductance catheter system. MATERIALS AND METHODS: Young and old male Fischer 344 rats were assigned to sedentary controls groups(young control group YC, old control group OC), and an exercise training group (old trained group OT). After 12-week treadmill exercise training (6 mo of age and 25 mo of age, respectively), the cardiac performance at different preloads was assessed using the Millar Pressure-Volume conductance catheter system. RESULTS: Heart rate (HR), mean arterial pressure, LV systolic pressure, maximal slope of the systolic pressure increment (+dP/dt), and maximal slope of the diastolic pressure decrement (-dP/dt) were decreased in OC compared with YC (all p<0.05). However, LV end diastolic pressure, end diastolic volume (EDV), end systolic volume, time constant of LV pressure decay (tau), and the slope of the end-diastolic pressure-volume relation (EDPVR slope) significantly increased in OC compared with YC (all p<0.05). After 12-week exercise training, HR, +dP/dt (p<0.05), and -dP/dt (p=0.07) were increased, but EDV, EDPVR slope (p<0.05), and tau (p=0.1) decreased in OT compared with OC. CONCLUSION: Longterm exercise training in old rats attenuated age-related deterioration in diastolic function. Our findings indicates that in rats, some age-associated changes in diastolic function are reversible and thus may not be intrinsic to aging.