Autonomic control of blood pressure and heart rate in obese
hypertensive dogs.
Truett, Alycia A., Agatha T. Borne, Michelle A. Poincot, and David B.
West.
Obesity, Diabetes and Metabolism Section, Pennington Biomedical
Research Center, Louisiana State University, Baton Rouge, Louisiana
70808, Department of Physiology, Louisiana State University Medical
Center, New Orleans, LA 70112
APStracts 2:0270R, 1995.
Autonomic control of cardiovascular function was evaluated in nine
dogs before and after a high-fat overfeeding regimen. Body weight
increased significantly (19.8+0.9kg to 29.5+2.1kg; p<.01) with
overfeeding. Mean arterial pressure (MAP) increased from 94.6+/
-2.1mmHg to 105.5+/-3.7mmHg (p<.05) and heart rate (HR) increased
from 94.8+/-3.5bpm to 112.3+/-5.6bpm (p<.01). Following
ganglionic blockade with chlorisondamine, dose response of MAP and HR
to methoxamine ([alpha]-agonist) or isoproterenol ([beta]-agonist)
was evaluated. Peak MAP response to methoxamine was blunted in obese
dogs. HR response to isoproterenol was not different between lean and
obese dogs. Atropine in the presence of propranolol increased heart
rate from 80.8+/-7bpm to 202.8+/-8.9bpm in lean dogs and from
113.8+/-12.1 to 131.7+/-18.2 in obese dogs. These data suggest the
increase in heart rate observed in obese dogs may be due to a
decrease in parasympathetic inhibition rather than an increase in
sympathetic stimulation. The blunted response to methoxamine in obese
hypertensive dogs suggests that the sympathetic control of peripheral
vascular resistance is altered in obesity.
Received 16 March 1995; accepted in final form 14 September 1995.
APS Manuscript Number R177-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 14 November 95