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.