Adrenoceptors involved in the contractile activity of islated pregnant rat uterus.
Cumulative log dose-response curves of soterenol, isoproterenol, phenylephrine and norepinephrine on isolated pregnant rat uterus at different days of gestation, were investigated. Soterenol produced a sustained inhibition of spontaneous motility during the whole pregnancy and this effect was blocked by butoxamine. The affinity of myometrium for the beta 2-adrenoceptor agonist was parallel to the concentration of progesterone in plasma during pregnancy. Isoproterenol, norepinephrine and phenylephrine caused dual, alpha- and beta-mediated responses, their relative dominance varied with the concentration and the days of pregnancy, alpha-Adrenoceptor effects of the amines coincided with increased plasma concentrations of estrogens, whereas beta ones were in parallel with the increment of plasma progesterone. It is concluded that: (a) there exist in the pregnant rat uterus beta 2-receptor-mediated responses influenced by the length of gestation; and (b) the concentration-pregnancy-dependent biphasic actions of isoproterenol, norepinephrine or phenylephrine suggest that their variable hormone-modulated ability interacts with both alpha- and beta-adrenoceptive uterine sites.
D000818:Animals; D002078:Butoxamine / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004967:Estrogens / Q000097:blood; D004983:Ethanolamines / Q000037:antagonists & inhibitors / Q000494:pharmacology; D005260:Female; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D009638:Norepinephrine / Q000494:pharmacology; D010477:Perfusion; D010656:Phenylephrine / Q000494:pharmacology; D011247:Pregnancy; D011270:Pregnancy, Animal; D051381:Rats; D011941:Receptors, Adrenergic / Q000187:drug effects*; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects*; D011943:Receptors, Adrenergic, beta / Q000187:drug effects*; D014590:Uterine Contraction / Q000187:drug effects*
D004967:Estrogens; D004983:Ethanolamines; D011941:Receptors, Adrenergic; D011942:Receptors, Adrenergic, alpha; D011943:Receptors, Adrenergic, beta; D002078:Butoxamine; D010656:Phenylephrine; D007545:Isoproterenol; D009638:Norepinephrine