Effects of estrogen in vivo on coronary vascular resistance in
perfused rabbit hearts.
Yang, Tianen, Matthew N. Levy, Wulf H. Utian, James Goldfarb, and
George I. Gorodeski.
Division of Investigative Medicine, Mt. Sinai Medical Center, and
Departments of Reproductive Biology, and Physiology and biophysics,
Case Western Reserve University School of Medicine, Cleveland,
Ohio
APStracts 2:0172R, 1995.
Estrogen or its vehicle was given daily to 3 groups of ovariectomized
rabbits for various times, after which coronary flow was measured in
their isolated perfused hearts. In 1 group, intramuscular injections
of estrogen (40 g/kg) for 7 or 14 days increased coronary flow by 40
to 50 % (P < 0.05). In rabbits given estrogen intramuscularly
for 7 days, the coronary flow returned to the basal level within 7
days after the estrogen injections were discontinued. In a second
group of animals, intravenous injections of estrogen (10 g/kg) for 4
days increased the coronary flow by 45 % (P < 0.01). In a third
group, we administered the estrogen transdermally for 4 days, and we
measured the plasma estrogen levels at the end of this period. The
coronary flow in this group was increased by 52 % (P < 0.001),
and the plasma estrogen levels ranged from 39 to 800 pg/ml. In all
groups of experiments, the increments in coronary flow evoked by
estrogen were virtually abolished by NG-nitro-L-arginine, an
inhibitor of nitric oxide synthase. We conclude that estrogen
regulates coronary blood flow, in part by upregulating nitric oxide
synthase in the coronary vasculature.
Received 29 December 1994; accepted in final form 7 June 1995.
APS Manuscript Number R740-4.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 11 July 1995.