The role of EDRF in the modulation of blood pressure and vascular reactivity in estrogen-treated rats.
The role of EDRF in the modulation of blood pressure and vascular reactivity in estrogen-treated rats was investigated both in vivo and in vitro studies. In vivo, long-term subcutaneous injection of ethinyl estradiol (EE2, 0.2 micrograms/day, s.c.) for 6 weeks significantly induced an elevation of systolic blood pressure from 117.1 +/- 2.7 to 129.9 +/- 3.6 mmHg. In vitro, the endothelium-dependent relaxation of ACh (10(-8)-10(-5) M) in intact aortic rings from EE2-treated rats was significantly blunted compared with normal control rats. Meanwhile, the contractile responses to PE (10(-8)-10(-5) M) was no difference between intact and denuded aortic rings from EE2-treated rats. The results indicate that the reduction of vasodilator response to ACh and the loss of enhanced contractile responses to PE in denuded rings may be due to altered endothelial function after long-term treatment with EE2. Furthermore, the high potassium (12.5-62.5 mM) induced-contraction and nitroglycerin (3 x 10(-8)-3 x 10(-6) M) induced-relaxation were not different between EE2 and control groups. These results indicate that the function of vascular smooth muscle did not alter after long-term treatment with EE2. In conclusion, the alteration of function of endothelium may play an important role in the modulation of estrogen-induced mild hypertension.
National Taipei College of Nursing, Taiwan, R.O.C.
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Wu
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001011:Aorta / Q000187:drug effects; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D004997:Ethinyl Estradiol / Q000494:pharmacology; D005260:Female; D009569:Nitric Oxide / Q000502:physiology*; D005996:Nitroglycerin / Q000494:pharmacology; D009994:Osmolar Concentration; D010656:Phenylephrine / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D014661:Vasoconstriction; D014664:Vasodilation; D014666:Vasomotor System / Q000187:drug effects / Q000502:physiology*
D010656:Phenylephrine; D009569:Nitric Oxide; D004997:Ethinyl Estradiol; D005996:Nitroglycerin; D000109:Acetylcholine; D011188:Potassium