Epithelial Electrolyte Transport Physiology and the Gasotransmitter Hydrogen Sulfide

Figure 1

Sources of hydrogen sulfide. (a) Environmental hydrogen sulfide (H₂S) occurs due to geothermal activities such as volcanoes, sulfur deposits, or sulfur springs. The pictures show the Halema‘uma‘u crater (top) and sulfur deposit (bottom) on Hawaii Big Island. (b) Microbial production of H₂S. Sulfate-reducing bacteria dissimilate sulfate into H₂S via dissimilatory sulfite reductase (DSR). Mesophilic bacteria use orthologues of the mammalian H₂S-generating enzymes cystathionine-β-synthase (CBS), cystathionine-γ-lyase (CSE), and 3-mercaptopyruvate sulfurtransferase (3MST) in order to generate H₂S from cysteine. (c) Mammalian cells produce H₂S from cysteine via CBS, CSE, and 3MST (1). H₂S can be stored in a reductant-labile intracellular pool as bound sulfane sulfur (2). The degradation of H₂S occurs via oxidative metabolic pathways in mitochondria (3).

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