Postjunctional alpha2-adrenoceptors in the rat tail artery: effect of sex and castration.
To investigate sex-related differences in vasoconstrictor responses to postjunctional alpha2-adrenoceptor activation, isolated ring segments of tail arteries from Fischer-344 rats were studied. Addition of the alpha2-adrenoceptor agonist, UK-14304 [5-bromo-6-(2-imidazoline-2yl)-aminol-quinoxaline], enhanced vasoconstriction to the selective alpha1-adrenoceptor agonist, methoxamine, in arteries from both males and females. The response to UK-14304 was significantly greater in arteries from males as compared to female arteries. Addition of alpha2-adrenoceptor antagonist, idazoxan or rauwolscine, shifted norepinephrine concentration response curves to the right. Antagonist effects also tended to be greater in arteries from males as compared to females. After gonadectomy, male-female differences persisted; thus, removal of sex hormones in either males or females did not alter responses to either agonists or antagonists of alpha2-adrenoceptors. These findings suggest that sex differences in alpha2-adrenoceptor function are not maintained by either male or female gonadal steroid hormones but may be developmentally regulated.
Department of Pharmacology, College of Medicine, University of California, Irvine 92697-4625, USA.
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Chen
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Duckles
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Krause
D058647:Adrenergic alpha-2 Receptor Agonists; D058669:Adrenergic alpha-2 Receptor Antagonists; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000818:Animals; D001158:Arteries / Q000187:drug effects / Q000378:metabolism; D000068438:Brimonidine Tartrate; D002369:Castration; D005260:Female; D012739:Gonadal Steroid Hormones / Q000378:metabolism; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology; D011810:Quinoxalines / Q000494:pharmacology; D051381:Rats; D011916:Rats, Inbred F344; D018341:Receptors, Adrenergic, alpha-2 / Q000378:metabolism*; D012727:Sex Characteristics; D013623:Tail; D014662:Vasoconstrictor Agents / Q000494:pharmacology*
D058647:Adrenergic alpha-2 Receptor Agonists; D058669:Adrenergic alpha-2 Receptor Antagonists; D000316:Adrenergic alpha-Agonists; D012739:Gonadal Steroid Hormones; D011810:Quinoxalines; D018341:Receptors, Adrenergic, alpha-2; D014662:Vasoconstrictor Agents; D000068438:Brimonidine Tartrate; D009638:Norepinephrine