title: Experimental evidence suggesting that nitric oxide diffuses from tissue into blood but not from blood into tissue.
abstract: The aim of this study was to evaluate in vivo whether nitric oxide (NO) is able to diffuse from blood into tissues and vice versa from tissues into blood. We used an in vivo model of intestinal ischemia (superior mesenteric artery occlusion) selectively increasing NO levels in intestinal tissue and an infusion of L-arginine selectively increasing NO levels in blood. In this model we followed formation of nitrosyl complexes of hemoglobin (Hb-NO) in blood and nitrosyl-diethyldithiocarbamate-iron complexes (DETC--Fe--NO) in ischemic intestine and normoxic tissues by means of electron paramagnetic resonance spectroscopy. NO trapping by DETC--Fe in the tissues resulted in a reduction of Hb--NO levels in blood accompanied by the formation of water-insoluble DETC--Fe-NO complexes in ischemic intestine and normoxic tissues both during ischemia and during reperfusion. Administration of L-arginine increased NO levels in blood but neither in ischemic intestine nor in normoxic tissue. Our data suggest that NO released in blood from endothelial cells does not diffuse into tissue. In contrast, NO formed in tissue diffuses into blood. The latter indicates that NO formed in tissues may exert its biological activities systematically.
authors.affiliation: L. Boltzman Institute for Experimental and Clinical Traumatology, Vienna, Austria. audrey.kozlov@vu-wien.ac.at
authors.forename: A V
authors.initials: AV
authors.lastname: Kozlov
authors.forename: B
authors.initials: B
authors.lastname: Sobhian
authors.forename: G
authors.initials: G
authors.lastname: Costantino
authors.forename: H
authors.initials: H
authors.lastname: Nohl
authors.forename: H
authors.initials: H
authors.lastname: Redl
authors.forename: S
authors.initials: S
authors.lastname: Bahrami
mesh_terms: D000818:Animals; D001120:Arginine / Q000008:administration & dosage; D004195:Disease Models, Animal; D004050:Ditiocarb / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D004578:Electron Spin Resonance Spectroscopy; D004912:Erythrocytes / Q000378:metabolism; D005296:Ferrous Compounds / Q000097:blood / Q000737:chemistry / Q000378:metabolism; D006454:Hemoglobins / Q000378:metabolism; D007262:Infusions, Intravenous; D007410:Intestinal Diseases / Q000097:blood / Q000209:etiology / Q000378:metabolism; D007413:Intestinal Mucosa / Q000378:metabolism; D007511:Ischemia / Q000097:blood / Q000209:etiology / Q000378:metabolism; D008297:Male; D009569:Nitric Oxide / Q000097:blood / Q000378:metabolism* / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D052250:Nitric Oxide Synthase Type III; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D005296:Ferrous Compounds; D006454:Hemoglobins; C085124:diethyldithiocarbamate iron(II); C008657:nitrosyl hemoglobin; D009569:Nitric Oxide; D001120:Arginine; D004050:Ditiocarb; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; C496316:Nos3 protein, rat