17 beta-Estradiol induces a rapid, endothelium-dependent, sex-specific vasodilatation in spontaneous constricted rat arterioles.
OBJECTIVE
Our purpose was to resolve the apparent contradiction between the endothelium-dependent and endothelium-independent vasodilator effects of 17 beta-estradiol reported in different studies.


METHODS
The inner diameters of isolated pressurized spontaneously constricted muscle arterioles (diameter = 63 microm) from Wistar rats (n = 21) were measured during exposure to 17 beta-estradiol, and the role of the endothelium and the influence of sex were assessed.


RESULTS
A dose-dependent dilatation was observed during exposure to 17 beta-estradiol concentrations from 10(-10) to 10(-4) mol/L. Arterioles of female rats displayed significantly more dilatation than vessels from male rats. The dilatation was significantly less in endothelium-denuded arterioles or after pretreatment with and in the presence of a nitric oxide synthase inhibitor.


CONCLUSIONS
These results provide strong evidence that, in addition to an endothelium-independent effect, 17 beta-estradiol has a dose-dependent, endothelium-mediated, rapid vasodilatory effect on muscle arterioles from the rat, which is stronger in female rats than in male rats.
Project Aging Women, and the Institute for Cardiovascular Research-Vrije Universiteit, Department of Obstetrics and Gynecology, VU University Medical Center, Amsterdam, The Netherlands.
Ramon G V
RG
Smolders
Marius J
MJ
van der Mooren
Peter
P
Kenemans
Peter W J
PW
van der Linden
Coen D A
CD
Stehouwer
Pieter
P
Sipkema
D000818:Animals; D001160:Arterioles / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D004727:Endothelium / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D066298:In Vitro Techniques; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D009213:Myography; D019335:Nitroarginine / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D012737:Sex Factors; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology
D004791:Enzyme Inhibitors; D019335:Nitroarginine; D004958:Estradiol