[Effect of N-palmitoylethanolamine on energy-dependent transport of Ca2+ in vesicles of myometrium sarcolemma and their phospholipid composition].

N-palmitoylethanolamine (NPE) was studied for their effect on calcium pump of pig myometrium sarcolemma. NPE in concentration of 10 microM, stimulated by 28-46% Mg2+, ATP-dependent accumulation of Ca2+ in vesicles of plasmatic membrane of uterus myocytes taking absolutely no effect on passive release of this cation from them. NPE modified phospholipid composition of sarcolemma, causing the increase of percentage content of phosphatidylinositol (by 20.2%) and lysophosphatidylcholine (2.7 times). While NPE effects transport Ca2+, Mg(2+)-ATPase solubilized from plasmatic membrane and purified due to the method of affinity chromatography on calmodulin-sepharose 4B, no activating effect of NPE on the calcium pump was observed. And what is more, a weakly expressed tendency to inhibition (by 14-15%, respectively) of the rate of Ca2+, Mg(2+)-dependent enzymic hydrolysis of ATP has been revealed. It is supposed that the effect of NPE on active transmembrane transport of Ca2+ is an important link in the general mechanism of contraction-relax of the myometrium and is, apparently, connected with its modifying effect on the lipid composition of the sarcolemma.