Influences of gender on sympathetic nerve responses to static
exercise.
Ettinger, Steven M., David H. Silber, Belinda G. Enders, Kristen S.
Gray, Greg Sutliff, Sandra K. Whisler, Joseph M. McClain, Michael B.
Smith, Qing X. Yang, Lawrence I. Sinoway.
Division of Cardiology and Department of Radiology, The Milton S.
Hershey Medical Center, The Pennsylvania State University, Hershey,
PA 17033 and Lebanon Veterans Administration Medical Center, Lebanon,
PA 17042
APStracts 2:0414A, 1995.
We compared reflex responses to static handgrip at 30% maximal
voluntary contraction (MVC) in 26 untrained men (mean age 35+/-3 yrs)
and 23 untrained women (mean age 39+/-4 yrs). Women demonstrated
attenuated increases in blood pressure and sympathetic nerve activity
(MSNA, microneurography) as compared to men. This difference was also
observed during a period of post-handgrip circulatory arrest. 31P NMR
spectroscopy studies demonstrated attenuations in the production of
H2PO4- and the development of cellular acidosis in women as compared
to men. Subjects also performed ischemic handgrip to fatigue. During
this paradigm MSNA responses were similar in the 2 groups suggesting
that freely perfused conditions are necessary for the full expression
of the gender effect. Finally, we examined MSNA responses to adductor
pollicus exercise in 7 (26+/-1 yrs) men and 6 (25+/-2 yrs) women. MVC
values and times to fatigue were similar in the two groups (MVC
men:4.3+/-0.4 kg; women:4.0+/-0.3 kg;NS. Time to fatigue men:209+/-16
sec; women 287+/-50 sec;NS). At periods of end exercise and post
exercise circulatory arrest, MSNA responses were attenuated in the
women as compared to the men. We conclude that during non-ischemic
static exercise sympathetic neural outflow is less in women as
compared to men. This response is due to an attenuated metaboreflex
in women. Finally, based on the adductor pollicus experiments, this
effect appears independent of muscle mass, workload and the level of
training.
Received 7 July 1995; accepted in final form 29 August 1995.
APS Manuscript Number A736-5.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 31 October 95