Hydrogen sulfide: a novel signaling molecule in the vascular system.

Hydrogen sulfide (H2S) is an endogenous gasotransmitter produced in mammalian cells. It is responsible for physiological functions in many organs and systems, with attention focused mainly on the cardiovascular and nervous systems. In the vascular system, H2S produces biphasic effects in regulation of vascular tone. At lower concentrations, it induces vasoconstriction predominantly via decreasing cyclic adenosine monophosphate in smooth muscle cell and inhibiting the production and bioavailability of nitric oxide. At higher concentrations, it produces vasorelaxation mainly through opening of KATP channels and induction of intracellular acidification. Scavenging reactive oxygen species and elevation of cyclic guanosine monophosphate are also implicated in the vasorelaxant response. This review presents an overview of the current knowledge of H2S in the vascular system, with special emphasis and discussion on the involvement of various signaling pathways and ion channels based on current understanding and reported literature till date.