Abstract
The gaseous molecule hydrogen sulfide (H(2)S) has been proposed as an endogenous signal molecule and neuromodulator in mammals. Using a newly developed method, we report here for the first time the ability of intact and living brain and colonic tissue in the mouse to generate and release H(2)S. This production occurs through the activity of two enzymes, cystathionine-gamma-lyase and cystathionine-beta-synthase. The quantitative expression of messenger RNA and protein localization for both enzymes are described in the liver, brain, and colon. Expression levels of the enzymes vary between tissues and are differentially distributed. The observation that, tissues that respond to exogenously applied H(2)S can endogenously generate the gas, strongly supports its role as an endogenous signal molecule.