Involvement of nitrosothiols, nitric oxide and voltage-gated K+ channels in photorelaxation of vascular smooth muscle.
The effects of nitrosothiol depleting compounds (p-hydroxymercuribenzoate, iodacetamide and ethacrynic acid), a guanylyl cyclase inhibitor (1H[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, ODQ) and nitric oxide (NO) scavenger agents (xanthine/xanthine oxidase and 2-(4-carboxyphenyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide; carboxy-PTIO) on light-induced photorelaxation in rat thoracic aorta were investigated. Photorelaxation responses were decreased in the presence of nitrosothiol depleting compounds suggesting S-nitrosothiols as the tissue source of the NO, whereas reduction in photorelaxation by the guanylyl cyclase inhibitor and NO scavenger agents indicates involvement of both NO and cGMP in photorelaxation. In addition the sensitivity of photorelaxation to the voltage-gated potassium channel (KV) inhibitor, 4-aminopyridine, indicates that photorelaxation is mediated via a NO/cGMP-dependent, and, perhaps, direct light, activation of KV channels.
Lovren
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Department of Pharmacology and Therapeutics and Smooth Muscle Research Group, Faculty of Medicine, University of Calgary, Alberta, Canada.
Triggle
C R
CR
D001565:Benzoates / Q000494:pharmacology; D004976:Ethacrynic Acid / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D006902:Hydroxymercuribenzoates / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology; D066298:In Vitro Techniques; D008027:Light; D009126:Muscle Relaxation / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects*; D009569:Nitric Oxide / Q000502:physiology*; D011188:Potassium / Q000378:metabolism; D026902:Potassium Channel Blockers; D015221:Potassium Channels / Q000502:physiology*; D011480:Protease Inhibitors / Q000494:pharmacology; D012974:Sodium Iodide / Q000494:pharmacology; D019820:Xanthine / Q000378:metabolism / Q000494:pharmacology; D014969:Xanthine Oxidase / Q000378:metabolism / Q000494:pharmacology
D001565:Benzoates; D006902:Hydroxymercuribenzoates; D007093:Imidazoles; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D011480:Protease Inhibitors; C030601:4-hydroxymercuribenzoate; C079393:1,3-dihydroxy-4,4,5,5-tetramethyl-2-(4-carboxyphenyl)tetrahydroimidazole; D019820:Xanthine; D009569:Nitric Oxide; D014969:Xanthine Oxidase; D012974:Sodium Iodide; D004976:Ethacrynic Acid; D011188:Potassium