Endothelium-dependent vasodilation of proximal coronary arteries
from exercise trained pigs.
Oltman, Christine L., Janet L. Parker, and M. Harold Laughlin.
Departments of Veterinary Biomedical Sciences, and Medical
Physiology, and Dalton Cardiovascular Research Center, University of
Missouri, Columbia, MO 65211
APStracts 2:0080A, 1995.
We recently reported that [alpha]-adrenergic vasoconstriction is
blunted and adenosine-induced vasodilation is enhanced in proximal
coronary arteries of exercise trained miniature swine (Am.J.Physiol.
263 H372,1992). The purpose of the present study was to determine
whether this model of exercise training also alters endothelium
-dependent vasodilator responses of proximal coronary arteries. Female
Yucatan miniature swine were exercise trained (ET) on a motor driven
treadmill or cage confined (SED) for 13 to 20 weeks. Exercise
tolerance, heart weight/body weight ratios and skeletal muscle
oxidative capacity were all significantly greater in ET than SED.
Vasodilator responses were evaluated in vitro by determining
concentration-response curves, using vascular rings (3.5 - 4 mm in
axial length) isolated from right and left coronary arteries.
Vasorelaxation responses were determined, after tone had been
produced with either 30 [mu]M PGF2[alpha], 30 mM KCl, or 30 nM
endothelin. Concentration-response curves were obtained to
endothelium-dependent vasodilators including: bradykinin (10-9 - 10-6
M), substance P (10-12 - 10-6 M), clonidine (10-9 - 10-6 M),
serotonin (10-10 - 10-5 M), and the Ca2+ ionophore, A23187 (10-10 -
10-6 M). Endothelium-independent vasodilator responses to sodium
nitroprusside (10-9 - 10-4 M)(SNP) were not different between
arteries from SED and ET. Bradykinin, substance P, and A23187 were
potent vasodilators in arteries from both groups whereas serotonin
and clonidine did not consistently produce vasodilation. There were
no significant differences between the vasodilator responses of
arteries from ET and SED pigs for any agent used in this study. We
conclude that endothelium-dependent vasodilation of proximal coronary
arteries is not altered in exercise trained miniature swine.
Received 3 November 1994; accepted in final form 17 February
1995.
APS Manuscript Number A1131-4.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 10 March 1995.