title: Mediation of nitric oxide from photosensitive stores in the photorelaxation of the rabbit corpus cavernosum.
abstract: Isolated rabbit corpus cavernosum relaxed in response to ultraviolet (UV) light (365 nm). The UV light-induced relaxation (photorelaxation) was diminished on repeated UV irradiation from 30.5+/-4.0% (the first photorelaxation) to 15.5+/-2.7% (the last photorelaxation). Hydroxocobolamine of 100 microM and hemoglobin (Hb) of 10 microM, which are nitric oxide (NO) scavengers, and 10 microM 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), a soluble guanylyl cyclase inhibitor, markedly reduced photorelaxation. However, 300 microM 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide (carboxy-PTIO) failed to inhibit photorelaxation. NaNO(2) and N(G)-nitro-L-arginine (L-NA) but not 3-nitro-L-tyrosine (3-NT) were found to be photosensitive in that these compounds are photolysed to release NO, as demonstrated by use of an amperometric NO probe; NO signals produced by 500 microM NaNO(2), and 500 microM L-NA were 133.3+/-28.9 and 54.4+/-10.4 pA, respectively. Not 3-NT but the other compounds (all 200 microM) also enhanced photorelaxation of the cavernosal tissue. Based on these findings, the substance, which mediates photorelaxation, could be NO released from putative stores in the rabbit corpus cavernosum, and L-NA as well as NaNO(2) but not 3-NT produce NO under the influence of UV light.
authors.affiliation: Department of Pharmacology, Medical Faculty, Mersin University, Campus Yenişehir, 33169, Mersin, Turkey. kbuyukafsar@mersin.edu.tr
authors.forename: Kansu
authors.initials: K
authors.lastname: Büyükafşar
authors.forename: Adnan
authors.initials: A
authors.lastname: Levent
authors.forename: Ismail
authors.initials: I
authors.lastname: Un
authors.forename: Mustafa
authors.initials: M
authors.lastname: Ark
authors.forename: Onur
authors.initials: O
authors.lastname: Arikan
authors.forename: Elif
authors.initials: E
authors.lastname: Ozveren
mesh_terms: D000818:Animals; D066298:In Vitro Techniques; D008297:Male; D009569:Nitric Oxide / Q000037:antagonists & inhibitors / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D010413:Penis / Q000187:drug effects / Q000502:physiology*; D011817:Rabbits; D014466:Ultraviolet Rays; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology*
chemical_list: D020030:Nitric Oxide Donors; D009569:Nitric Oxide