Babich L. Mechanisms of Са2+ transporting systems regulation in the myometrium cells.

It was shown that TrpC1, TrpC2, TrpC4, TrpC5, TrpC6 and TrpC7 mRNAs were expressed in rat myometrium, in women myometrium - the same forms; however TrpC3 instead TrpC2. Rat TrpC5 and TrpC6 mRNA expression decreased in pregnancy. Women's labor was accompanied by the decline of TrpC4 mRNA expression. In the presence of valinomycin, K+ gradient stimulated the initial rate of energy-dependent Ca2+ accumulation in the plasma membrane vesicles. It was shown, that co-functioning of the cationic antiporter and Ca-pump fully prevented the dissipation of the initial oppositely directed Ca2+ gradient. Relaxation of myometrium carbachole contracture is controlled by the plasma membrane calcium pump. It was shown that spermine in the concentration from 1 to 10 mМ partly inhibited the accumulation of Са2+ in sarcoplasmic reticulum. However at increase of spermine concentration in a range 0,1-1 mM stimulation of Ca2+ accumulation in mitochondria was observed, at the further increase in polyamine concentration up to 10 mM suppression of this process took place. Ca2+ accumulation in mitochondria was completely inhibited by 10 ?М calmidazolium or 100 ?М trifluoperazine, known as calmodulin antagonists. It was also shown that these calmodulin antagonists caused mitochondria membrane depolarization. It was shown, that Mg2+ (7 mM) addition to the incubation medium induced mitochondrial membrane hyperpolarization. Addition of Ca2+ leads to membrane potential dissipation. Mg2+ (7 mM) preliminary presence in the incubation medium did not protect mitochondria from Ca2+-induced depolarization.