title: L-NIL prevents renal microvascular hypoxia and increase of renal oxygen consumption after ischemia-reperfusion in rats.
abstract: Even though renal hypoxia is believed to play a pivotal role in the development of acute kidney injury, no study has specifically addressed the alterations in renal oxygenation in the early onset of renal ischemia-reperfusion (I/R). Renal oxygenation depends on a balance between oxygen supply and consumption, with the nitric oxide (NO) as a major regulator of microvascular oxygen supply and oxygen consumption. The aim of this study was to investigate whether I/R induces inducible NO synthase (iNOS)-dependent early changes in renal oxygenation and the potential benefit of iNOS inhibitors on such alterations. Anesthetized Sprague-Dawley rats underwent a 30-min suprarenal aortic clamping with or without either the nonselective NO synthase inhibitor N(omega)-nitro-L-arginine methyl ester (L-NAME) or the selective iNOS inhibitor L-N(6)-(1-iminoethyl)lysine hydrochloride (L-NIL). Cortical (CmicroPo(2)) and outer medullary (MmicroPo(2)) microvascular oxygen pressure (microPo(2)), renal oxygen delivery (Do(2ren)), renal oxygen consumption (Vo(2)(ren)), and renal oxygen extraction (O(2)ER) were measured by oxygen-dependent quenching phosphorescence techniques throughout 2 h of reperfusion. During reperfusion renal arterial resistance and oxygen shunting increased, whereas renal blood flow, CmicroPo(2), and MmicroPo(2) (-70, -42, and -42%, respectively, P < 0.05), Vo(2)(ren), and Do(2ren) (-70%, P < 0.0001, and -28%, P < 0.05) dropped. Whereas L-NAME further decreased Do(2ren), Vo(2)(ren), CmicroPo(2), and MmicroPo(2) and deteriorated renal function, L-NIL partially prevented the drop of Do(2ren) and microPo(2), increased O(2)ER, restored Vo(2)(ren) and metabolic efficiency, and prevented deterioration of renal function. Our results demonstrate that renal I/R induces early iNOS-dependent microvascular hypoxia in disrupting the balance between microvascular oxygen supply and Vo(2)(ren), whereas endothelial NO synthase activity is compulsory for the maintenance of this balance. L-NIL can prevent ischemic-induced renal microvascular hypoxia.
authors.affiliation: Department of Translational Physiology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands. m.legrand@libertysurf.fr
authors.forename: Matthieu
authors.initials: M
authors.lastname: Legrand
authors.forename: Emre
authors.initials: E
authors.lastname: Almac
authors.forename: Egbert G
authors.initials: EG
authors.lastname: Mik
authors.forename: Tanja
authors.initials: T
authors.lastname: Johannes
authors.forename: Asli
authors.initials: A
authors.lastname: Kandil
authors.forename: Rick
authors.initials: R
authors.lastname: Bezemer
authors.forename: Didier
authors.initials: D
authors.lastname: Payen
authors.forename: Can
authors.initials: C
authors.lastname: Ince
mesh_terms: D000818:Animals; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D000860:Hypoxia / Q000188:drug therapy* / Q000378:metabolism; D007668:Kidney / Q000098:blood supply / Q000187:drug effects / Q000378:metabolism; D008239:Lysine / Q000031:analogs & derivatives* / Q000494:pharmacology; D008833:Microcirculation / Q000187:drug effects; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000037:antagonists & inhibitors / Q000378:metabolism; D010101:Oxygen Consumption / Q000187:drug effects*; D009195:Peroxidase / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012079:Renal Circulation / Q000187:drug effects*; D015427:Reperfusion Injury / Q000188:drug therapy* / Q000378:metabolism; D012964:Sodium / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; C090663:N(6)-(1-iminoethyl)lysine; D009569:Nitric Oxide; D012964:Sodium; D009195:Peroxidase; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat; D008239:Lysine; D019331:NG-Nitroarginine Methyl Ester