[Effect of uterine contraction stimulants on active and passive transport of Ca2+ in the fraction of myometrium sarcolemma].

Effect of drugs (quinine, sigetine, isoverine and pachycarpine) stimulating uterine contraction on active and passive Ca2+ transport was studied in cow myometrium sarcolemma. Isoverine and pachycarpine at concentrations 10(-6)-10(-2) M did not affect the systems of Ca2+ transport. Quinine at concentrations above 10(-3) M decreased the rate of Mg2+ ATP-dependent accumulation of Ca2+ and stimulated passive elimination of the cation from vesicles due to an increase in unspecific permeability of myometrial sarcolemma. Sigetine (10(-6) = 10(-2) M) did not affect the Ca2+ passive transport but inhibited uncompetitively the Mg2+ ATP-dependent accumulation of Ca2+ in sarcolemmal vesicles. Effect of sigetine as a stimulator of the uterine contractile activity is apparently based on inhibition of the calcium pump in plasmatic membrane of myometrial cells.