The functional and molecular studies on involvement of hydrogen sulphide in myometrial activity of non-pregnant buffaloes (Bubalus bubalis)

BACKGROUND Hydrogen sulphide (H2S), a member of the gasotransmitters family, is known to play patho-physiological role in different body systems including during pregnancy. But its involvement in myometrial spontaneity and associated signalling pathways in uterus in non-pregnant animals is yet to be studied. Present study describes the effect of L-cysteine, an endogenous H2S donor, on isolated myometrial strips of non-pregnant buffaloes and the underlying signaling mechanism(s). RESULTS L-cysteine (10 nM-30 mM) produced concentration-dependent contractile effect on buffalo myometrium which was extracellular Ca2+ and L-type calcium channels-dependent. Significant rightward shift of dose-response curve of L-cysteine was observed with significant decrease in maxima in the presence of amino-oxyacetic acid (AOAA; 100 μM) and d, l-propargylglycine (PAG; 100 μM), the specific blockers of cystathionine β-synthase (CBS) and cystathionine γ-lyase (CSE), respectively. Existence of CBS enzyme of 63 kDa and CSE of 45 kDa molecular weights was confirmed by western blot using specific antibodies and also by immunohistochemistry. CONCLUSIONS Endogenous H2S along with its biosynthetic enzymes (CBS and CSE) is evidently present in uteri of non-pregnant buffaloes and it regulates spontaneity in uteri of non-pregnant buffaloes and this effect is dependent on extracellular Ca2+ influx through nifedipine-sensitive L-type calcium channels. Thus H2S-signalling pathway may be a potential target to alter the uterine activities in physiology and patho-physiolgical states.