A novel pathway for the production of H2S by DAO in rat jejunum

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Hydrogen sulfide (H2S) is endogenously generated from L-cysteine (L-Cys) by the enzymes cystathionine-β-synthase (CBS) and cystathionine-γ-Lyase (CSE). Hydrogen sulfide is also produced from D-cysteine (D-Cys) by D-Amino acid oxidase (DAO).


The H2S production was measured by the methylene blue assay. The expression of DAO was investigated by Western blotting and immunohistochemistry. The short-circuit current (Isc) was recorded using the Ussing chamber technique.

Key Results

The epithelium in rat jejunum possesses DAO, and generates H2S. D-cysteine, originally used as a negative control for L-Cys, significantly increases the H2S release, which is inhibited by I2CA, an inhibitor of DAO. In vitro study by Ussing chamber technique reveals that D-Cys decreases the Isc across the epithelium of the rat jejunum and enhances the Na+-coupled L-alanine transport.

Conclusions & Inferences

A novel pathway for the production of H2S by DAO exists in rat jejunum.

Hydrogen sulfide is produced from D-cysteine (D-Cys) in rat jejunum. D-Amino acid oxidase (DAO) exists in rat jejunum. D-cysteine evokes a short-circuit current across epithelium of rat jejunum. D-cysteine enhances the Na+-coupled L-alanine transport.

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