Delayed and diminished pressor response to muscle sympathetic nerve
activity in the elderly.
Sugiyama, Yoshiki, Toshiyoshi Matsukawa, A. S. M. Shamsuzzaman,
Hisashi Okada, Takemasa Watanabe, and Tadaaki Mano.
Department of Autonomic and Behavioral Neurosciences, Division of
Higher Nervous Control, Research Institute of Environmental Medicine,
Nagoya University
APStracts 2:0481A, 1995.
We studied the effects of aging on [alpha]-receptor-mediated
vasoconstrictive responses to sympathetic nerve activity in sixteen
healthy aged (75.8+/-2.7 yrs, means+/-SE) and young men (33.8+/-2.0
yrs). Muscle sympathetic nerve activity (MSNA), heart rate and blood
pressure were analyzed during slow respiration (0.1 Hz). Peak
amplitude and phase were calculated from a cosine function fitted
with 0.1 Hz by using the least squares method. The latency of the
pressor response to MSNA, lag time from the peak of MSNA to diastolic
blood pressure, was significantly longer in the aged than the young
group (7.1+/-0.3 vs. 5.4+/-0.4 sec, p<0.01). The extent of
pressor response to MSNA, diastolic blood pressure rise in response
to increase in total MSNA, was significantly lower in the aged than
the young group (0.038+/-0.006 vs. 0.099+/-0.024 mmHg/unit,
p<0.001). These results suggest that [alpha]-receptor-mediated
vasoconstrictive responses to MSNA may be attenuated in the elderly.
Received 17 October 1994; accepted in final form 23 October 1995.
APS Manuscript Number A1070-4.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 30 November 95