title: Prompt effect of progesterone on the adrenergic response of smooth muscles.
abstract: The contractile effects of epinephrine on the uterus and ductus deferens of the rabbit and the ductus deferens of the monkey were inhibited by the preincubation with progesterone (6.4 X 10(-5) M) for 1 or 3 min in Locke-Ringer solution. Epinephrine relaxed the guinea pig uterus and taenia caecum. The relaxant effects were enhanced by preincubation with progesterone. Their effects were in a dose-dependent manner. There was no apparent change in the number and affinity of alpha-adrenergic receptors in the uterus of rabbits and the ductus deferens of guinea pigs during the incubation with progesterone. Progesterone has no direct effect on alpha-adrenergic receptors. All smooth muscles yielded reproducible contractile reactions to Ca2+ when maintained in depolarizing Tyrode's solution containing K+ (40 mmol/l). Their concentration-response curves were inhibited by preincubation with progesterone (6.4 X 10(-5) M), and they were shifted to the right in a concentration-dependent manner. Established Ca2+-induced contractions were rapidly relaxed by the addition of progesterone (6.4 X 10(-5) M). It suggests that progesterone directly affects the plasma membrane and inhibits the voltage-dependent Ca2+ channel and then inhibits smooth muscle contraction.
mesh_terms: D000818:Animals; D002118:Calcium / Q000502:physiology*; D002432:Cecum / Q000187:drug effects; D004837:Epinephrine / Q000502:physiology*; D005260:Female; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008251:Macaca; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects*; D011374:Progesterone / Q000378:metabolism / Q000494:pharmacology*; D011817:Rabbits; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects; D013045:Species Specificity; D014590:Uterine Contraction / Q000187:drug effects; D014649:Vas Deferens / Q000187:drug effects
chemical_list: D011942:Receptors, Adrenergic, alpha; D011374:Progesterone; D002118:Calcium; D004837:Epinephrine