Effect of estrogen treatment on calcium uptake by the rat uterine smooth muscle

The effect of estrogenization on cellular 45Ca uptake by the isolated uterine strips was studied. Whereas estrogenization 1 h before sacrifice of ovariectomized rats caused no significant change in Ca uptake by the isolated uteri, exposure to estrogen 24 h before sacrifice resulted in a significant increase in uptake. Following continuous exposure for 72 h to estrogen, the uptake of Ca was increasd by more than two-fold. Increased Ca uptake following estrogenization may largely account for the increased contractile responses of the uterine smooth muscle particularly those induced by potassium depolarization.