Making and working with hydrogen sulfide: The chemistry and generation of hydrogen sulfide in vitro and its measurement in vivo: A review

Hydrogen sulfide is rapidly emerging as an important vasoactive mediator formed in health and disease. Its biological action is centered on its reactivity with heme-proteins and its ability to activate K_ATP channels. Hydrogen sulfide is a signalling molecule of the inflammatory and nervous systems, and in particular the cardiovascular system where it regulates vascular tone, cardiac work, and exerts cardioprotection.This has led to an explosion of papers in which the role of hydrogen sulfide generated in vitro has been used to stimulate biological responses, and where a variety of methods have been used to measure the concentration of this compound in biological fluids. Understanding the chemistry and the inherent problems in the analytical techniques used to measure hydrogen sulfide concentrations is critical to our expanding knowledge on the biology of hydrogen sulfide. In this brief review we will cover the chemistry of hydrogen sulfide, including sources of hydrogen sulfide, its speciation at physiological pH, the susceptibility of sulfide to aerobic oxidation, and the methods used to measure hydrogen sulfide concentrations in solution, including biological fluids. We also give a brief overview of knockout animals and inhibition of the enzymes involved in the formation of hydrogen sulfide in vivo.