Title:Hydrogen sulfide and the metabolic syndrome

Hydrogen sulfide (H2 S) is one of three gasotransmitter molecules besides nitric oxide (NO) and carbon monoxide, which has emerged as an endogenous physiological regulator/modulator in the cardiovascular, nervous, immune and other systems in the body [1,2] , wherein the known toxicity of H2 S is tamed by the miniscule quantities produced. The enzymes that produce H 2 S from Lcysteine are cystathionine γ-lyase (CSE) and cystathionine [beta]-synthase (CBS) [1,3] . CSE predominates in the cardiovascular system and CSE-knockout mice develop hypertension and demonstrate reduced endothelium-dependent relaxation of resistance arteries, indicating a physiological role of H2 S in blood pressure (BP) regulation [4] . Various aspects of the pathophysiology of H2 S have been covered in other reviews in this issue. Before discussing research on H2 S and its role in the metabolic syndrome, we will briefly discuss the pathophysiology of the metabolic syndrome.