β-cyano-L-Alanine (BCA) is a reversible inhibitor of the H2S-synthesizing enzyme CTH (CSE). BCA blocks H2S synthesis activity in rat liver preparations with an IC50 value of 6.5 μM and increases blood pressure in anaesthetized rats induced with hemorrhagic shock by inhibiting endogenous H2S synthesis. BCA at 50 mg/kg blocked both L-cysteine- and LPS-induced hyperalgesia in rats. Hydrogen sulfide (H2S) is a naturally-occurring gasotransmitter with vasodilator and inflammatory modulating activity. H2S is synthesized naturally in a range of mammalian tissues principally by the activity of two enzymes, CTH (cystathionine γ lyase CSE) and cystathionineβ synthetase (CBS).
