title: Dose- and time-dependence of radiation-induced nitric oxide formation in mice as quantified with electron paramagnetic resonance.
abstract: In vivo nitric oxide (NO) formation was quantified in mice after exposure to high-dose whole-body X-ray irradiation. NO produced and accumulated in the livers of irradiated mice was determined using NO trapping method with iron-dithiocarbamate complex combined with electron paramagnetic resonance (EPR) spectroscopy. When mice were irradiated with 50 Gy X-ray, NO formation peaked in approximately 3 h after the irradiation was terminated. Dose-dependence study indicated that NO formation measured 5 h after irradiation was leveled off at the dose higher than 50 Gy. Administration of NO synthase inhibitor, N(G)-monomethyl L-arginine (L-NMMA) shortly after irradiation completely abolished the NO signal, indicating that radiation-induced NO is produced through L-arginine-dependent NO synthase pathways. These results suggest that irradiation of X-ray initiates inflammation processes, resulting in delayed NO synthase expression and NO formation.
authors.affiliation: Department of Bioregulation Research, National Institute for Radiological Sciences, Inage, Chiba 263, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Nakagawa
authors.forename: N
authors.initials: N
authors.lastname: Ikota
authors.forename: T
authors.initials: T
authors.lastname: Ozawa
authors.forename: Y
authors.initials: Y
authors.lastname: Kotake
mesh_terms: D000818:Animals; D001120:Arginine / Q000378:metabolism; D004307:Dose-Response Relationship, Radiation; D004578:Electron Spin Resonance Spectroscopy; D004790:Enzyme Induction / Q000528:radiation effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D007249:Inflammation / Q000209:etiology / Q000378:metabolism*; D008099:Liver / Q000378:metabolism*; D051379:Mice; D008813:Mice, Inbred ICR; D009569:Nitric Oxide / Q000096:biosynthesis*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D052247:Nitric Oxide Synthase Type II; D011829:Radiation Dosage; D011833:Radiation Injuries, Experimental / Q000378:metabolism*; D013012:Sorbitol / Q000031:analogs & derivatives / Q000737:chemistry; D013113:Spin Labels; D013859:Thiocarbamates / Q000737:chemistry; D013997:Time Factors; D014916:Whole-Body Irradiation; D019323:omega-N-Methylarginine / Q000494:pharmacology
chemical_list: D004791:Enzyme Inhibitors; D013113:Spin Labels; D013859:Thiocarbamates; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D013012:Sorbitol; C041262:N-methyl-D-glucamine dithiocarbamate; D001120:Arginine; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse