Daily exercise and gender influence the arterial baroreflex
regulation of heart rate and nerve activity.
Chen, Chao-Yin, and Stephen E. Dicarlo.
Department of Physiology, Northeastern Ohio Universities, College
of Medicine, Rootstown, Ohio 44272
APStracts 3:0204H, 1996.
The influence of daily spontaneous running (DSR) and gender on the
arterial baroreflex regulation of heart rate (HR) and lumbar
sympathetic nerve activity (LSNA) was examined in thirteen male (7
sedentary, SED and 6 DSR) and twelve female (6 SED and 6 DSR)
Sprague-Dawley rats. After 8-9 wk of DSR or sedentary control, all
animals were chronically instrumented with right femoral venous and
left carotid arterial catheters and electrodes around the lumbar
sympathetic trunk. DSR resulted in an increase in heart weight-to
-body weight ratio (p = 0.001) in male and female rats and resting
bradycardia in male rats (p = 0.001). Arterial baroreflex function
was examined by ramp increases (1.25 +/- 0.07 mmHg/s) and decreases
(1.47 mmHg/s) in arterial pressure. DSR attenuated the arterial
baroreflex regulation of LSNA in a similar manner in female and male
rats. DSR reduced the range (32% and 29% for female and male rats,
respectively), maximum (26% and 21% for female and male rats,
respectively), and Gmax (46% and 17% for female and male rats,
respectively). In contrast, there was a gender influence on the
arterial baroreflex regulation of HR. For example, SED female rats
had a higher maximum gain (Gmax, 40%) than SED male rats.
Furthermore, DSR altered the arterial baroreflex regulation of HR
differently in male and female rats. DSR female rats had a reduced
Gmax (38%), range (25%) and maximum (12%) while DSR male rats had a
reduced maximum (17%) and minimum (23%). These results demonstrate
that: 1) DSR attenuated the arterial baroreflex regulation of LSNA in
a similar manner in female and male rats. 2) In contrast, DSR altered
the arterial baroreflex regulation of HR differently in female and
male rats.
Received 16 January 1996; accepted in final form 25 April 1996.
APS Manuscript Number H28-6.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 19 May 96