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Query: UMLS:C0020500 (hyperoxaluria)
 912 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Nitrosative stress plays a role in calcium oxalate stone formation, as nitrosated proteins have been identified in stone formers. Nitric oxide (NO(*)), the common precursor for reactive nitrogen species, is synthesized in the juxtaglomerular apparatus of the kidneys. The present study is aimed to determine the role of nitric oxide synthase (NOS) in an experimental hyperoxaluric condition by histological and biochemical techniques. Hyperoxaluria was induced by 0.75% ethylene glycol in drinking water. L-arginine (L-arg) was supplemented at a dose of 1.25 g/kg body weight orally for 28 days. Nitric oxide metabolites (NOx), protein content in the urine and lipid peroxidation in the kidney were determined at the end of the experimental period. Histopathological examination of the rat kidneys was then carried out. NADPH-diaphorase and eNOS expression studies were carried out in control and hyperoxaluric rat kidneys using histochemical and immunohistochemical techniques. Significant amounts of NOx were present in the urine of hyperoxaluric animals when compared to control rats. Histopathological examinations revealed membrane injury, tubular dilatation and edema in the hyperoxaluric rats, whereas co-supplementation of L-arg to the hyperoxaluric rats significantly reduced these changes. The results of histochemical analysis for NADPH-diaphorase staining demonstrate the role of NOS in hyperoxaluric rats. Hyperoxaluric rats showed intense staining for NADPH-diaphorase when compared to control and L-arg co-supplemented hyperoxaluric rats. Immunohistochemical demonstration confirmed that eNOS expression was markedly increased in L-arg supplemented rats, when compared to EG treated rat kidney sections. Thus, from the present study, we conclude that supplementation of L-arg to the hyperoxaluric animals minimizes the cellular injury mediated by ethylene glycol, prevents oxidative/nitrosative damage to the membranes and reduces the incidence of calcium oxalate stone formation.
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PMID:Detection of endothelial nitric oxide synthase and NADPH-diaphorase in experimentally induced hyperoxaluric animals. 1600 48

Hyperoxaluric kidneys show an impaired diuretic response to acute infusion of L-arginine. In this study, we examined the chronic effect of l-arginine supplementation on CaOx crystal formation in hyperoxaluric rat kidneys. Eight groups were tested: control (received drinking water), L group (received L-arginine, 0.6%), LN group [received NG-nitro-L-arginine methyl ester (L-NAME, 10 mg/kg)], L + LN group (received L-arginine + l-NAME), HP group [received hydroxyl-L-proline (HP, 5%) mixed with chow to induce hyperoxaluria], L + HP group (received HP + L-arginine), HP + LN group, and L + HP + LN group. The duration was 42 days, and each group had eight animals. Urinary biochemistry and renal CaOx amounts were measured, as well as renal expressions of nitric oxide synthase (NOS) isoforms and NAD(P)H oxidase. The distribution of inducible NOS (iNOS), NAD(P)H oxidase, ED1-positive cells, and nitrotyrosine was examined by immunohistochemical and immunofluorescence studies, whereas superoxide production from the kidneys was examined by fluorescence spectrometric assay. Compared with the HP group, the L + HP group had excessive CaOx crystal accumulation and enhanced endothelial NOS (eNOS), iNOS, and NAD(P)H oxidase protein expression in the kidney. Urinary excretion of nitrotyrosine was markedly increased. Increased superoxide formation in the L + HP kidney was derived from NAD(P)H oxidase and uncoupled eNOS, and increased nitrotyrosine formation might derive from iNOS and ED1-positive cells that gathered around the CaOx crystals. L-NAME cotreatment (L + HP + LN group) reduced renal oxidative nitrosative stress and tubular damage, which were induced by L + HP. The results showed that chronic l-arginine treatment to the hyperoxaluric kidney with massive CaOx crystal deposition may have a toxic effect by enhancing intrarenal oxidative and nitrosative stress.
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PMID:Chronic L-arginine administration increases oxidative and nitrosative stress in rat hyperoxaluric kidneys and excessive crystal deposition. 1844 92