title: Increase in peripheral blood flow due to extraocular direct irradiation of visible light in rats.
abstract: We have conducted experiments to clarify the existence of extraretinal photosensitivity in mammals through the measurements of skin blood flow variation due to light irradiation. We found that blood flow shows a synchronized transient increase with a irradiation-nonirradiation sequence. The action spectrum of the phenomenon was found to show peaks at approximately 410-420 nm, 540-550 nm, and 570- 580 nm. These peaks coincide with the specific optical absorption peaks of B and Q (alpha,beta) bands in sixfold coordinated ferruos-heme complexes such as nitric oxide (NO)-Hb. The blood flow increase in the irradiated duration disappears when the rats are intraperitoneally injected with 1H-[1,2,3]oxydiazolo[4,3-a] quinoxalin-1-one (ODQ), which is an inhibitor of guanylate cyclase, and N(G)-monomethyl-L-arginine acetate and N(G)-nitro-L-arginine methyl ester, which are inhibitors of NO synthase. On the basis of the present results, we propose a photochemical model of the photosensitivity mechanism where optical absorption of the sixfold coordinated ferrous heme-NO complex plays a main role.
authors.affiliation: The Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka 567-0047, Japan. koba_kei@sp8sun.spring8.or.jp
authors.forename: K
authors.initials: K
authors.lastname: Kobayashi
authors.forename: Y
authors.initials: Y
authors.lastname: Kobayashi
authors.forename: A
authors.initials: A
authors.lastname: Hashida-Okumura
authors.forename: S
authors.initials: S
authors.lastname: Iimori
authors.forename: K
authors.initials: K
authors.lastname: Nagai
authors.forename: H
authors.initials: H
authors.lastname: Nakashima
mesh_terms: D000818:Animals; D001783:Blood Flow Velocity / Q000187:drug effects / Q000528:radiation effects*; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000008:administration & dosage; D005135:Eye Protective Devices; D007274:Injections, Intraperitoneal; D017078:Laser-Doppler Flowmetry; D007834:Lasers; D008027:Light; D008297:Male; D019331:NG-Nitroarginine Methyl Ester / Q000008:administration & dosage; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D009599:Nitroprusside; D010069:Oxadiazoles / Q000008:administration & dosage; D010396:Penicillamine / Q000008:administration & dosage / Q000031:analogs & derivatives*; D011810:Quinoxalines / Q000008:administration & dosage; D051381:Rats; D017208:Rats, Wistar; D012039:Regional Blood Flow / Q000187:drug effects / Q000528:radiation effects; D012867:Skin / Q000098:blood supply* / Q000528:radiation effects*; D013623:Tail; D014665:Vasodilator Agents / Q000008:administration & dosage; D019323:omega-N-Methylarginine / Q000008:administration & dosage
chemical_list: C095284:1H-(1,2,4)oxadiazolo(4,3-a)quinoxalin-1-one; D004791:Enzyme Inhibitors; D010069:Oxadiazoles; D011810:Quinoxalines; C110881:S-nitro-N-acetylpenicillamine; D014665:Vasodilator Agents; D009599:Nitroprusside; D019323:omega-N-Methylarginine; D019001:Nitric Oxide Synthase; D010396:Penicillamine; D019331:NG-Nitroarginine Methyl Ester