Yonsei Med J.  2000 Feb;41(1):49-55. 10.3349/ymj.2000.41.1.49.

Estrogen affects vascular tone differently according to vasoactive substances in ovariectomized Sprague-Dawley rat

Affiliations
  • 1Department of Internal Medicine, College of Medicine, Gyeongsang National University, Chinju, Korea. bgseo@nongae.gsnu.ac.kr
  • 2Department of Cardiovascular Research Institute, College of Medicine, Gyeongsang National University, Chinju, Korea.
  • 3Division of Genetics, International Center for Medical Research, Kobe University School of Medicine, Japan.

Abstract

The favorable effects of estrogen on cardiovascular diseases can be explained by several mechanisms such as changes in serum lipid profiles and thrombogenecity. Estrogen also affects the vascular tone, but there has been no report in which the effect of estrogen was tested comprehensively for several vasoactive substances, especially after long-term administration. Two weeks after bilateral ovariectomy in 8-week old female Sprague-Dawley rats, placebo or 17 beta-estradiol (E2) pellets (0.5 mg; released over 3 weeks) were implanted subcutaneously. Two weeks after pellet implantation, organ chamber experiments were performed using aortae. Compared with control, E2-treated vessels showed impaired endothelium-dependent relaxation to acetylcholine. E2 enhanced the contraction to norepinephrine and U46619 and had no effect on endothelin-1-induced contraction. In contrast, the contraction to angiotensin (AT)-II was inhibited by E2. Northern blot analysis for AT1 receptor expression using cultured aortic smooth muscle cells showed no difference between control and E2-treated cells, suggesting that AT1 receptor downregulation is not the likely mechanism. These results suggest that E2 affects the vascular tone variably according to vasoactive substances.

Keyword

Estrogen; rat; aorta; ovariectomy; vascular tone; endothelium-dependent relaxation; norepinephrine; angiotensin II; U46619; endothelin-1

MeSH Terms

Animal
Estradiol/pharmacology*
Female
In Vitro
Ovariectomy*
Rats
Rats, Sprague-Dawley
Vasoconstrictor Agents/pharmacology*
Vasodilator Agents/pharmacology*
Vasomotor System/drug effects*
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