title: Gender differences in vascular reactivity to endothelin-1 in deoxycorticosterone-salt hypertensive rats.
abstract: In experimental models of hypertension, blood pressure reaches a higher level in male than in female rats. Because endothelin-1 (ET-1) seems to play a role in blood pressure elevation in deoxycorticosterone acetate (DOCA)-salt hypertension, we hypothesized that male DOCA-salt rats would display a greater vascular responsiveness to ET-1 than female DOCA-salt rats. Male and female Wistar rats were uninephrectomized, received DOCA injections (50 mg/kg/week) and water plus 1.0% NaCl/0.2% KCl. Control rats received vehicle and tap water. Responses to ET-1, norepinephrine (NE), serotonin (5-HT), IRL-1620, a selective endothelin-B- (ET(B)) receptor agonist, and acetylcholine (ACh) were evaluated in isolated aortic rings and also in vivo in the mesenteric microcirculation. Endothelium-intact aortas from male and female DOCA rats displayed increased sensitivity (p < 0.05) to NE and 5-HT, but decreased relaxation to ACh in comparison to aortas from respective control male and female rats. Endothelium-denuded, but not endothelium-intact, arteries from male DOCA rats displayed increased sensitivity (-log EC20) to ET-1, but no changes in ET-1 sensitivity were observed in female DOCA aortas. IRL-1620 induced contraction in male DOCA aortas, but not in female DOCA or control endothelium-denuded aortas. In the microcirculation, IRL-1620 induced vasodilation in male and female control rats, but marked vasoconstriction in male DOCA and minimal changes in vessels diameter in female DOCA rats. Bosentan, an ET(A)/ET(B)-receptor antagonist, induced a greater decrease in mean arterial blood pressure in male than in female DOCA-salt hypertensive rats. These data support the hypothesis that DOCA-salt rats exhibit gender differences in ET-1 vascular reactivity, which probably result from functional changes in ET(B)-receptors. The increased ET(B) responses in male DOCA-salt hypertensive rats may play a role in their higher blood pressure levels.
authors.affiliation: University of Sao Paulo, Institute of Biomedical Science, Department of Pharmacology, SP, Brazil.
authors.forename: R C
authors.initials: RC
authors.lastname: Tostes
authors.forename: F L
authors.initials: FL
authors.lastname: David
authors.forename: M H
authors.initials: MH
authors.lastname: Carvalho
authors.forename: D
authors.initials: D
authors.lastname: Nigro
authors.forename: R
authors.initials: R
authors.lastname: Scivoletto
authors.forename: Z B
authors.initials: ZB
authors.lastname: Fortes
mesh_terms: D000818:Animals; D003900:Desoxycorticosterone / Q000494:pharmacology*; D019332:Endothelin-1 / Q000494:pharmacology*; D016232:Endothelins / Q000494:pharmacology; D005260:Female; D006973:Hypertension / Q000503:physiopathology*; D066298:In Vitro Techniques; D008297:Male; D010446:Peptide Fragments / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D012727:Sex Characteristics; D012965:Sodium Chloride / Q000494:pharmacology*; D014661:Vasoconstriction / Q000187:drug effects*
chemical_list: D019332:Endothelin-1; D016232:Endothelins; D010446:Peptide Fragments; C074308:sovateltide; D003900:Desoxycorticosterone; D012965:Sodium Chloride