Calcium channel, Ca++ mobilization, and mechanical reactivity of estrogen- and progesterone-treated rat uterus.
Properties of [3H]nitrendipine binding, high K+- and Ca++-induced contractions and the inhibition of high K+-induced contractions by verapamil were investigated in the uterine preparations isolated from rats treated with estrogen or progesterone or both. In [3H]nitrendipine binding experiments using crude membrane fractions, treatment with estrogen alone or estrogen+progesterone significantly lowered the KD; There was very little change in the Bmax. In the Ca++-depleted, high K+-containing medium, only the progesterone-, and estrogen----progesterone-treated uteri produced contractions. The estrogen-, estrogen----progesterone-, and estrogen+progesterone-treated uteri showed decreases in concentrations of Ca++ required for the maximal contractions. In the estrogen- and estrogen+progesterone-treated uteri, the dose-response curves by verapamil were shifted to the left in a parallel manner. These findings suggest that estrogen appeared to increase the affinity of calcium channels and increase transmembrane influx of Ca++, leading to enhancement of contractions, whereas progesterone might increase the Ca++ storage in the intracellular sites.
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000378:metabolism; D015220:Calcium Channels; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D066298:In Vitro Techniques; D007473:Ion Channels / Q000187:drug effects / Q000502:physiology*; D007700:Kinetics; D009543:Nifedipine / Q000031:analogs & derivatives / Q000378:metabolism; D009568:Nitrendipine; D011188:Potassium / Q000494:pharmacology; D011374:Progesterone / Q000494:pharmacology*; D051381:Rats; D011978:Receptors, Nicotinic / Q000378:metabolism; D014590:Uterine Contraction / Q000187:drug effects; D014599:Uterus / Q000187:drug effects / Q000502:physiology*; D014700:Verapamil / Q000494:pharmacology
D002121:Calcium Channel Blockers; D015220:Calcium Channels; D007473:Ion Channels; D011978:Receptors, Nicotinic; D011374:Progesterone; D004958:Estradiol; D009568:Nitrendipine; D014700:Verapamil; D009543:Nifedipine; D011188:Potassium; D002118:Calcium