title: Characterization of ultraviolet light-induced relaxation of the isolated duodenum of the rat.
abstract: 1 Isolated duodenum of the rat, exposed to ultraviolet (u.v.) light in the presence of NO2 ions, responded with reversible relaxation. 2 The photorelaxation response did not seem to involve any known receptor mechanisms and was independent of any ganglionic or neuronal influences. 3 Changes in the ionic environment of the tissue showed that NA+ and Ca2+ were essential for the photorelaxation. K+ depolarized-tissue did not show the photoresponse. 4 The presence of the metabolic inhibitors, iodoacetic acid, 2,4-dinitrophenol, sodium fluoride, sodium azide or potassium cyanide, abolished the photorelaxation response. 5 It is proposed that the photorelaxation of the tissue resulted from the liberation of metabolic energy following NO2 ion-dependent absorption of u.v. light energy, which in turn, interfered with the Na+ ion movement across the cell membrane.
mesh_terms: D000818:Animals; D004305:Dose-Response Relationship, Drug; D004386:Duodenum / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects*; D007700:Kinetics; D009119:Muscle Contraction / Q000528:radiation effects*; D009126:Muscle Relaxation / Q000187:drug effects / Q000528:radiation effects*; D009573:Nitrites / Q000494:pharmacology; D051381:Rats; D014466:Ultraviolet Rays
chemical_list: D009573:Nitrites