text: Hydrogen sulfide (H(2)S), a regulatory gaseous molecule that is endogenously synthesized by cystathionine gamma-lyase (CSE) and/or << cystathionine beta-synthase >> (CBS) from [[ L-cysteine ]] (L-Cys) metabolism, is a putative vasodilator, and its role in nitric oxide (NO) production is unexplored.