Abstract
Background: Hydrogen sulfide (H2S) is recognized as a gaseous transmitter in mammalian tissues. Several physiological roles for H2S including vasodilation, and smooth muscle relaxation have been documented. The exact mechanism explaining its role in uterine contractility remain to be elucidated. The proposed study was conducted to elucidate H2S role in uterine contractility in relation to adrenergic and cholinergic systems. Methods: Isolated uterus horn of adult virgin female sprage Dawely rats were used in vitro in physiological saline solution, the effects of H2S donor (NaHS), H2S blocker aminooxiacetic acid (AOAA) with or without adrenergic and cholinergic drugs and glibenclamide were determined. Results: It was revealed that, NaHS inhibited myometrial contractions as regard the tone and amplitude, whereas AOAA increased the tone of uterine contractility. The relaxant effect of H2S on uterine contractility was mediated by modulation of the endogenous adrenergic and cholinergic systems in the myometrium, which was demonstrated by dual interaction of NaHS or AOAA with Adrenaline, Propranolol, Prazosin, Acetylcholine and Atropine on the tone, peak, amplitude and frequency of uterine contractions. Glibencalmide (KATP channels blocker) after NaHS significantly increased the tone, peak and amplitude. However Glibencalmide after AOAA produced no significant changes in the tone, peak and amplitude of uterine contractions. Conclusion: H2S has a relaxant action in smooth muscles of myometrium. This inhibitory effect of H2S on uterine contractility could be through dual interaction and modulation of the endogenous adrenergic and cholinergic systems and activation of KATP channels.