Endothelin-1 sensitivity of porcine coronary arteries is reduced by
exercise training and is gender dependent.
Jones, Allan W., Leona J. Rubin, and Lawrence Magliola.
Departments of Physiology, Veterinary Biomedical Sciences and
Dalton Cardiovascular Research Center, University of Missouri,
Columbia, Columbia, MO 65212
APStracts 6:0242A, 1999.
We tested the hypothesis that exercise training reduces the
sensitivity of coronary smooth muscle to endothelin-1 (ET-1) with the
adaptation being greater in male than in female miniature swine. The
efficacy of training was similar in males and females. Cumulative ET
-1 contractile responses of coronary branches and left circumflex
artery were significantly shifted to the right in exercise trained
(EX) males, but not in EX females. Analyses of the EC50 showed a 1.7
to 2.2 fold shift in EX males with no change in maximum tension. Non
-selective blockade of K-channel activity with tetraethylammonium
(TEA, 30-50 mM) significantly shifted the EC50 to a lower
concentration in both EX males (1.25 fold) and EX females (2.2 fold),
but not in sedentary (SED) groups. Females (combined SED and EX)
exhibited a greater response to TEA than combined males. Changes in
[32P] phosphatidic acid ([32P]PA) provided an indicator of ET-1
induced phospholipase activity. The magnitude of the [32P]PA response
was reduced by EX in both males and females without affecting the
EC50. It is concluded that the contractile sensitivity of coronary
arteries to ET-1 is influenced by physical activity in a gender
dependent manner. It is unclear why the contractile sensitivity in
females was not reduced by EX as in the males, since EX significantly
affected responses to TEA and ET-1 stimulation of [32P]PA production
in both males and females. A potential gender difference in K-channel
function may contribute to this discrepancy.
Received 7 May 1998; accepted in final form 21 May 1999.
APS Manuscript Number A409-8.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1999 The American Physiological Society.
Published in APStracts on 14 June 1999