BAROREFLEX CONTROL OF MUSCLE SYMPATHETIC-NERVE ACTIVITY IS ATTENUATEDIN THE ELDERLY

To determine whether the baroreflex control of sympathetic nerve activ ity is attenuated in the elderly, muscle sympathetic nerve activity (M SNA) from the tibial nerve was monitored using microneurography, and h eart rate and blood pressure were recorded during the depressor (phase II) or presser (phase IV) period to Valsalva's maneuver in 10 younger subjects and 7 aged subjects. The baroreflex slope for heart rate sho wed attenuation in the aged subjects during the pressor phase but not during the depressor phase, the baroreflex slope for MSNA was also att enuated in the aged subjects during the presser and tended to be atten uated during the depressor phases. These data suggest impaired baroref lex function for both heart rate and sympathetic nerve activity in the elderly. (C) 1998 Elsevier Science B.V. All rights reserved.