Calcium accumulation by human uterine microsomal preparations: Effects of progesterone and oxytocin.
A microsomal fraction was prepared from human pregnant uteri at term and at 6 to 19 weeks' gestation, and from nonpregnant uteri by differential centrifugation and purified on a discontinuous sucrose density gradient. This fraction bound calcium in the presence of adenosine triphosphate (ATP). ATP-dependent calcium binding in microsomal preparations was found to increase with advancing pregnancy. Addition of progesterone increased the ATP-dependent calcium binding, while addition of oxytocin decreased the ATP-dependent calcium binding. In combination, oxytocin and progesterone counteracted each other. The progesterone effect was specific for progesterone; three biologically inactive analogues had no effects on calcium binding. The actions of progesterone and of oxytocin on ATP-dependent calcium binding were found to be consistent with their respective in vivo uterine relaxing and contracting actions.
D000255:Adenosine Triphosphate / Q000494:pharmacology*; D001665:Binding Sites / Q000187:drug effects; D002118:Calcium / Q000037:antagonists & inhibitors / Q000378:metabolism*; D003470:Culture Media; D004336:Drug Antagonism; D005260:Female; D006801:Humans; D006908:Hydroxyprogesterones / Q000494:pharmacology; D008861:Microsomes / Q000378:metabolism*; D009215:Myometrium / Q000166:cytology*; D010121:Oxytocin / Q000494:pharmacology*; D011247:Pregnancy; D011276:Pregnanediol / Q000494:pharmacology; D011277:Pregnanediones / Q000494:pharmacology; D011374:Progesterone / Q000494:pharmacology*; D014590:Uterine Contraction; D014599:Uterus / Q000166:cytology*
D003470:Culture Media; D006908:Hydroxyprogesterones; D011277:Pregnanediones; D011374:Progesterone; D010121:Oxytocin; D000255:Adenosine Triphosphate; D011276:Pregnanediol; D002118:Calcium