title: Mechanism of vasorelaxation and role of endogenous hydrogen sulfide production in mouse aorta.
abstract: This study aimed to elucidate the molecular mechanism of H(2)S-induced vasorelaxation. Vasorelaxation responses to the H(2)S donor NaHS and the H(2)S precursor L: -cysteine were examined by measuring isometric tone of mouse aortic rings in a small vessel myograph. H(2)S concentrations in Krebs' solution were determined with a polarographic sensor. H(2)S expression was examined by Western blot, and H(2)S production from CSE was assayed using a spectroscopic method. In pre-constricted mouse aorta, NaHS (1 μM-3 mM) elicited vasorelaxation of 95 ± 7%, EC(50) 189 ± 69 μM. This response was unaffected by removal of the endothelium. Maximum vasorelaxation was significantly attenuated by global blockade of K(+) channels (50 mM K(+)) and the K(ATP) channel blocker glibenclamide (10 μM) alone (P < 0.01, ANOVA). Specific inhibition of K(Ca), K(IR), or K(V) channels elicited a significant shift to the right in the concentration-response curve to NaHS (P < 0.01, ANOVA) without affecting maximum relaxation. NaHS-mediated vasorelaxation was inhibited by the Cl(-) channel inhibitor DIDS (1 mM, P < 0.05, t test), and NaHS caused a significant concentration-dependent inhibition of voltage-gated Ca(2+) channels (P < 0.001, two-way ANOVA). The H(2)S-producing enzyme cystathionine-γ-lyase (CSE) was expressed in mouse aorta and had activity of 7 ± 3 μmol H(2)S/g/min. L: -cysteine (1 μM-3 mM) elicited a CSE-dependent vasorelaxation of mouse aorta with intact endothelium (20 ± 7%), but not when the endothelium was removed. CSE inhibitors DL: -propargylglycine (20 mM) and β-cyanoalanine (1 mM) caused concentration-dependent contraction of mouse aorta. In mouse aorta, H(2)S elicits endothelium-independent vasorelaxation involving several different ion channels and seems to converge at the vascular smooth muscle cell voltage-gated Ca(2+) channel. The L: -cysteine-CSE-H(2)S pathway contributes to vasorelaxation and appears to modulate basal vessel tone.
authors.affiliation: Department of Pharmacology, Monash University, Clayton, VIC, 3800, Australia.
authors.forename: Mohammad R
authors.initials: MR
authors.lastname: Al-Magableh
authors.forename: Joanne L
authors.initials: JL
authors.lastname: Hart
mesh_terms: D000818:Animals; D001011:Aorta / Q000187:drug effects / Q000378:metabolism*; D015153:Blotting, Western; D015220:Calcium Channels / Q000378:metabolism; D003542:Cystathionine gamma-Lyase / Q000378:metabolism; D003545:Cysteine / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism; D006862:Hydrogen Sulfide / Q000378:metabolism*; D007473:Ion Channels / Q000187:drug effects / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism; D009213:Myography; D013440:Sulfides / Q000008:administration & dosage / Q000494:pharmacology*; D014664:Vasodilation / Q000187:drug effects*
chemical_list: D015220:Calcium Channels; D007473:Ion Channels; D013440:Sulfides; D003542:Cystathionine gamma-Lyase; C025451:sodium bisulfide; D003545:Cysteine; D006862:Hydrogen Sulfide