Hydrogen sulfide inhibits the spontaneous and oxytocin-induced contractility of human pregnant myometrium

Hydrogen sulfide (H(2)S) is a novel endogenous gaseous signaling transmitter in mammalian tissues including smooth muscle tissues. We investigated the effect of sodium hydrosulfide (NaHS), a H(2)S donor, on the contractility of isolated human myometrium strips from term pregnant women who were undergoing labor. Cumulative effects of NaHS on spontaneous and oxytocin-induced contractility were evaluated by using isometric tension recordings. NaHS (0.1 μM-1 mM) concentration dependently inhibited spontaneous contractility of laboring myometrium, with a decrease in amplitude and frequency. NaHS (0.1 μM-1 mM) decreased the frequency but not the amplitude of oxytocin (1 μM)-induced contractions. NaHS-induced relaxation could be prevented by pretreatment with glibenclamide, an inhibitor of K(+)(ATP) channels. Thus, NaHS evokes relaxation of human pregnant myometrium, suggesting a possible role of H(2)S during human pregnancy.