Levitt, Michael D.

Hydrogen sulfide (H 2 S) has long been associated with the gastrointestinal tract, especially the bacteria-derived H 2 S present in flatus. Along with evidence from other organ systems, the finding that gastrointestinal tissues are capable of endogenous production of H 2 S has led to the hypothesis that H 2 S is an endogenous gaseous signaling molecule. In this review, the criteria of gasotransmitters are reexamined, and evidence from the literature regarding H 2 S as a gaseous signaling molecule is discussed. H 2 S is produced enzymatically by gastrointestinal tissues, but evidence is lacking on whether H 2 S production is regulated. H 2 S causes well-defined physiologic effects in gastrointestinal tissues, but evidence for a receptor for H 2 S is lacking. H 2 S is inactivated through enzymatic oxidation, but evidence is lacking on whether manipulating H 2 S oxidation alters endogenous cell signaling. Remaining questions regarding the role of H 2 S as a gaseous signaling molecule in the gastrointestinal tract suggest that H 2 S currently remains a molecule in search of a physiologic function. Antioxid. Redox Signal. 12, 1135–1146.