H2S is produced by enzymes and has various physiological roles including neuromodulation, vascular tone regulation, cytoprotection against oxidative stress. We previously demonstrated that H2S relaxes vascular smooth muscle in synergy with NO. In the process of the study about the effect of H2S on transient receptor potential (TRP) channels, we found that H2Sn activates TRP ankyrine 1 (TRPA1) channels much more potently than does H2S and that 3-mercaptopyruvate sulfurtransferase (3MST) produces H2S2 and H2S3. The chemical interaction of H2S with nitric oxide (NO) has been reported to generate several products including nitroxyl (HNO), nitrosopersulfide (HSSNO) and H2Sn. The effect of H2Sn on TRPA1 channels is suppressed by reduction and by cyanide, while that of HNO is resistant to reduction and that of HSSNO to cyanide. Based on these observations we concluded that H2Sn are chemical entities generated by the interaction of H2S with NO. I will focus on the production of H2Sn and a potential mechanism of the synergistic effect of H2S and NO.

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