title: Hydrogen sulfide-induced relaxation of resistance mesenteric artery beds of rats.
abstract: Hydrogen sulfide (H2S) has been shown recently to function as an important gasotransmitter. The present study investigated the vascular effects of H2S, both exogenously applied and endogenously generated, on resistance mesenteric arteries of rats and the underlying mechanisms. Both H2S and NaHS evoked concentration-dependent relaxation of in vitro perfused rat mesenteric artery beds (MAB). The sensitivity of MAB to H2S (EC50, 25.2 +/- 3.6 microM) was about fivefold higher than that of rat aortic tissues. Removal of endothelium or coapplication of charybdotoxin and apamin to endothelium-intact MAB significantly reduced the vasorelaxation effects of H2S. The H2S-induced relaxation of MAB was partially mediated by ATP-sensitive K+ (KATP) channel activity in vascular smooth muscle cells. Pinacidil (EC50, 1.7 +/- 0.1 microM, n=6) mimicked, but glibenclamide (10 microM, n=6) suppressed, the vasorelaxant effect of H2S. KATP channel currents in isolated mesenteric artery smooth muscle cells were significantly augmented by H2S. L-cysteine, a substrate of cystathionine-gamma-lyase (CSE), at 1 mM increased endogenous H2S production by sixfold in rat mesenteric artery tissues and decreased contractility of MAB. DL-propargylglycine (a blocker of CSE) at 10 microM abolished L-cysteine-dependent increase in H2S production and relaxation of MAB. Our results demonstrated a tissue-specific relaxant response of resistance arteries to H2S. The stimulation of KATP channels in vascular smooth muscle cells and charybdotoxin/apamin-sensitive K+ channels in vascular endothelium by H2S represents important cellular mechanisms for H2S effect on MAB. Our study also demonstrated that endogenous CSE can generate sufficient H2S from exogenous L-cysteine to cause vasodilation. Future studies are merited to investigate direct contribution of endogenous H2S to regulation of vascular tone.
authors.affiliation: Dept. of Physiology, College of Medicine, Univ. of Saskatchewan, 107 Wiggins Rd., Saskatoon, Saskatchewan, Canada S7N 5E5.
authors.forename: Youqin
authors.initials: Y
authors.lastname: Cheng
authors.forename: Joseph Fomusi
authors.initials: JF
authors.lastname: Ndisang
authors.forename: Guanghua
authors.initials: G
authors.lastname: Tang
authors.forename: Kun
authors.initials: K
authors.lastname: Cao
authors.forename: Rui
authors.initials: R
authors.lastname: Wang
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D003542:Cystathionine gamma-Lyase / Q000494:pharmacology; D006862:Hydrogen Sulfide / Q000378:metabolism / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D008638:Mesenteric Arteries / Q000166:cytology / Q000187:drug effects* / Q000502:physiology*; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000378:metabolism; D010656:Phenylephrine / Q000494:pharmacology; D015221:Potassium Channels / Q000378:metabolism / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013440:Sulfides / Q000494:pharmacology; D014655:Vascular Resistance; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014664:Vasodilation / Q000502:physiology; D014665:Vasodilator Agents / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D015221:Potassium Channels; D013440:Sulfides; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D010656:Phenylephrine; D000255:Adenosine Triphosphate; D003542:Cystathionine gamma-Lyase; C025451:sodium bisulfide; D006862:Hydrogen Sulfide