In vitro inhibition of rat uterine contractility induced by 5 alpha and 5 beta progestins.
Ten natural progestins were evaluated for their capacity to inhibit the in vitro motility of rat's uterus. Progestins with their ring A reduced in the 5 beta position were significantly more potent than delta 4-3 keto and 5 alpha reduced progestins. These last progestins were ineffective to inhibit uterine motility excepting 3 alpha-hydroxy-5 alpha-pregnan-20-one which was slightly less effective than progesterone. The potency of the progestins to inhibit uterine motility was related to their capacity to induce membrane stabilization. The data indicates that 5 beta, but not 5 alpha reduction of progesterone, may be important for regulating myometrial activity.
D004092:20-alpha-Dihydroprogesterone / Q000494:pharmacology; D000818:Animals; D004031:Diestrus; D004305:Dose-Response Relationship, Drug; D005260:Female; D007536:Isomerism; D011247:Pregnancy; D011276:Pregnanediol / Q000494:pharmacology; D011277:Pregnanediones / Q000494:pharmacology; D011278:Pregnanes / Q000494:pharmacology*; D011280:Pregnanolone / Q000494:pharmacology; D011374:Progesterone / Q000494:pharmacology; D011372:Progestins / Q000494:pharmacology*; D051381:Rats; D013237:Stereoisomerism; D013329:Structure-Activity Relationship; D014590:Uterine Contraction / Q000187:drug effects*
D011277:Pregnanediones; D011278:Pregnanes; D011372:Progestins; D004092:20-alpha-Dihydroprogesterone; D011374:Progesterone; D011280:Pregnanolone; D011276:Pregnanediol