Effect of aging on muscle sympathetic nerve activity and peripheral venous pressure in humans

To elucidate the effect of aging on blood pressure regulation, especially cardiopulmonary baroreflex in humans, we measured the resting value of muscle sympathetic nerve activity (MSNA), heart rate (HR), blood pressure (BP), peripheral venous pressure (PVP), and calf blood flow (CBF) in eight healthy young male subjects and eight healthy aged subjects, and compared the responses to the low level of lower body negative pressure (LBNP) between the two groups. The resting MSNA was higher, and the response of MSNA to LBNP was lower in the aged group than in the young group; the response of PVP to LBNP was also lower in the aged than in the young group. Delta MSNA/delta PVP showed no significant differences between the two groups. The present findings indicate that the effect of LBNP on cardiopulmonary baroreflex is greater in young people than in aged people, but that cardiopulmonary baroreflex may be preserved with advancing age.