[THE ROLE OF HYDROGEN SULFIDE IN VOLUME-DEPENDENT MECHANISMS OF REGULATION OF VASCULAR SMOOTH MUSCLE CELLS CONTRACTILE ACTIVITY].

The hydrogen sulfide (H2S) influence on the contractile activity of vascular smooth muscle cells (SMC) was studied on endothelium-denuded aortic ring segments of male Wistar rats with method of mechanography. Contractions of SMS were induced by incubation in high potassium solution as well as in hyper-, hypo- and isosmotic solutions. 5-100 LM of H2S donor--sodium hydrosulfide (NaHS) increased mechanical tension of SMC precontracted with high potassium solution that was abolished by bumetanide--the inhibitor of Na+, K+, 2Cl(-) -cotransporter (NKCC), but 100-1000 microM of NaHS relaxed SMS. NaHS (10 microM) increased the amplitude of hyper- and isosmotic contraction, but not of hyposmotic contraction. NaHS (ImM) decreased the amplitude of hyper-, iso-, and hyposmotic contractions. The direct measurements of NKCC activity with radionuclide method showed an increase in NKCC activity under the action of 5-100 microM of NaHS. These findings suggest that low concentrations of H2S participate in the NKCC activation. This mechanism underlines constrictive action of H2S on smooth muscle cells.