Role of Cyclic Nucleotides in the Effect of Hydrogen Sulfide on Contractions of Rat Jejunum.

We studied the role of cyclic nucleotides in the influence of hydrogen sulfide (H2S) donor, sodium hydrosulfide (NaHS, 200 μM), on motor activity of rat jejunum. NaHS reduced spontaneous and carbachol-induced contractions of rat jejunum segment, which suggests that H2S can act through mechanisms involving muscarinic receptor activation. Against the background of a membrane-penetrating non-hydrolyzable cAMP analogue or under conditions of adenylate cyclase blockade, the inhibitory effect of NaHS on the carbachol-induced contractions was maintained. Against the background of elevated cGMP concentration or guanylate cyclase inhibition, the reduction of carbachol-induced contractions upon exposure to NaHS was less pronounced than in control. It was hypothesized that H2S induces relaxation of carbachol-induced jejunum contractions, affecting protein kinase G targets or activating cGMP synthesis.