Estradiol relaxes rat aorta via endothelium-dependent and -independent mechanisms.
The effects of estrogen on arterial function are heterogeneous with respect to vessel and/or species. We have investigated 17beta-estradiol-induced relaxation in isolated rat aorta with regard to the role of the vascular endothelium and ionic mechanisms. Estrogen induced a concentration-dependent relaxation of 46.5 +/- 7.9% and 70.1 +/- 12.2% (10(-8) and 10(-7)M), which was reduced by endothelial denudation. Furthermore, L-nitroarginine methyl ester completely abrogated this effect; however, estradiol did not relax KCl-contracted rings. Tetraethyl ammonium (1 mmol/l) completely blocked estradiol-induced relaxation. Estradiol increased [cGMP] in isolated aortic rings via NO, but did not significantly affect NOS activity in endothelial cells. Thus, estrogen can relax rat aorta in vitro via both endothelium-dependent and -independent mechanisms involving the NO/cGMP and potassium channel signaling system.
Abou-Mohamed
Gamal
G
Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta, GA 30912, USA. gabou@mail.mcg.edu
Elmarakby
Ahmed
A
Carrier
Gerald O
GO
Catravas
John D
JD
Caldwell
Robert W
RW
White
Richard E
RE
D000818:Animals; D001011:Aorta / Q000187:drug effects*; D002417:Cattle; D006152:Cyclic GMP / Q000096:biosynthesis / Q000502:physiology; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000502:physiology*; D004958:Estradiol / Q000494:pharmacology*; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology; D009126:Muscle Relaxation / Q000187:drug effects / Q000502:physiology; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000096:biosynthesis / Q000502:physiology; D015221:Potassium Channels / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013997:Time Factors
D015221:Potassium Channels; D009569:Nitric Oxide; D004958:Estradiol; D006152:Cyclic GMP; D019331:NG-Nitroarginine Methyl Ester