Vasoconstrictive effect of hydrogen sulfide involves downregulation of cAMP in vascular smooth muscle cells

Abstract

Hydrogen sulfide (H2S), a new endogenous mediator, produces both vasorelaxation and vasoconstriction. This study was designed to examine whether cAMP mediates the vasoconstrictive effect of H2S. We found that NaHS at a concentration range of 10–100 μM (yields ∼3–30 μM H2S) concentration-dependently reversed the vasodilation caused by isoprenaline and salbutamol, two β-adrenoceptor agonists, and forskolin, a selective adenylyl cyclase activator, in phenylephrine-precontracted rat aortic rings. Pretreatment with NaHS (10–100 μM) for 5 min also significantly attenuated the vasorelaxant effect of salbutamol and forskolin. More importantly, NaHS (5–100 μM) significantly reversed forskolin-induced cAMP accumulation in vascular smooth muscle cells. However, NaHS produced significant, but weaker, vasoconstriction in the presence of NG-nitro-l-arginine methyl ester (100 μM), a nitric oxide synthase inhibitor, or in endothelium-denuded aortic rings. Blockade of ATP-sensitive potassium channels with glibenclamide (10 μM) failed to attenuate the vasoconstriction induced by H2S. Taken together, we demonstrated for the first time that the vasoconstrictive effect of H2S involves the adenyly cyclase/cAMP pathway.