Hosoki R, Matsuki N, Kimura H
Department of Chemical Pharmacology, Toho University Schol of Pharmaceutical Sciences, Chiba, Japan.
Biochem Biophys Res Commun. 1997 Aug 28;237(3):527-31. doi: 10.1006/bbrc.1997.6878.
Hydrogen sulfide (H2S), which is well known as a toxic gas, is produced endogenously in mammalian tissues from L-cysteine mainly by two pyridoxal-5'-phosphate-dependent enzymes, cystathionine beta-synthetase and cystathionine gamma-lyase. Recently, we showed that cystathionine beta-synthetase in the brain produces H2S, and that H2S facilitates the induction of hippocampal long-term potentiation by enhancing NMDA receptor activity. Here we show that mRNA for another H2S producing enzyme, cystathionine gamma-lyase, is expressed in the ileum, portal vein, and thoracic aorta. The ileum also expresses cystathionine beta-synthetase mRNA. These tissues produce H2S, and this production is blocked by cystathionine beta-synthetase and cystathionine gamma-lyase specific inhibitors. Although exogenously applied H2S alone relaxed these smooth muscles, much lower concentrations of H2S greatly enhanced the smooth muscle relaxation induced by NO in the thoracic aorta. These observations suggest that the endogenous H2S may regulate smooth muscle tone in synergy with NO.
硫化氢（H₂S）作为一种有毒气体广为人知，它在哺乳动物组织中主要由两种依赖磷酸吡哆醛 -5'-磷酸的酶，即胱硫醚β-合成酶和胱硫醚γ-裂解酶，从L-半胱氨酸内源性产生。最近，我们发现大脑中的胱硫醚β-合成酶能产生H₂S，并且H₂S通过增强NMDA受体活性促进海马体长期增强效应的诱导。在此我们表明，另一种产生H₂S的酶——胱硫醚γ-裂解酶的mRNA在回肠、门静脉和胸主动脉中表达。回肠也表达胱硫醚β-合成酶mRNA。这些组织能产生H₂S，且这种产生被胱硫醚β-合成酶和胱硫醚γ-裂解酶的特异性抑制剂所阻断。尽管单独外源性应用H₂S可使这些平滑肌舒张，但低得多的H₂S浓度能极大增强胸主动脉中由一氧化氮（NO）诱导的平滑肌舒张。这些观察结果表明，内源性H₂S可能与NO协同调节平滑肌张力。
