Nitric oxide synthesis and oxidative stress in the renal cortex of rats with diabetes mellitus.
Experiments were performed to test the hypothesis that diabetes mellitus disrupts the balance between synthesis and degradation of nitric oxide (NO) in the renal cortex. Diabetes was induced by injection of streptozotocin, and sufficient insulin was provided to maintain moderate hyperglycemia for the ensuing 2 wk. Despite an 80% increase in total NO synthase activity measured by L-citrulline assay, nicotinamide adenine dinucleotide phosphate-diaphorase staining was unaltered, and no changes in NO synthase isoform protein levels or their distribution were evident in renal cortex from diabetic rats. Superoxide anion production was accelerated twofold in renal cortical slices from diabetic rats, with an associated 50% increase in superoxide dismutase activity. Western blots prepared by use of a monoclonal antinitrotyrosine antibody revealed an approximately 70-kD protein in renal cortex from sham rats, the nitrotyrosine content of which was threefold greater in cortical samples from diabetic rats. These observations indicate that the early stage of diabetes mellitus provokes accelerated renal cortical superoxide anion production in a setting of normal or increased NO production. This situation can be expected to promote peroxynitrite formation, resulting in the tyrosine nitration of a single protein of unknown identity, as well as a decline in the bioavailability of NO. These events are consistent with the postulate that oxidative stress promotes NO degradation in the renal cortex during the early stage of diabetes mellitus.
Ishii
Naohito
N
Department of Physiology & Biophysics, University of Nebraska College of Medicine, Omaha, Nebraska.
Patel
Kaushik P
KP
Department of Physiology & Biophysics, University of Nebraska College of Medicine, Omaha, Nebraska.
Lane
Pascale H
PH
Department of Pediatrics, University of Nebraska College of Medicine, Omaha, Nebraska.
Taylor
Traci
T
Vascular Biology Center and Department of Pharmacology & Toxicology, Medical College of Georgia, Augusta, Georgia.
Bian
K A
KA
Department of Integrative Biology & Pharmacology, University of Texas Medical School at Houston, Houston, Texas.
Murad
Ferid
F
Department of Integrative Biology & Pharmacology, University of Texas Medical School at Houston, Houston, Texas.
Pollock
Jennifer S
JS
Vascular Biology Center and Department of Pharmacology & Toxicology, Medical College of Georgia, Augusta, Georgia.
Carmines
Pamela K
PK
Department of Physiology & Biophysics, University of Nebraska College of Medicine, Omaha, Nebraska.
D000818:Animals; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism*; D003922:Diabetes Mellitus, Type 1 / Q000378:metabolism; D007672:Kidney Cortex / Q000378:metabolism*; D008297:Male; D009252:NADPH Dehydrogenase / Q000378:metabolism; D009569:Nitric Oxide / Q000096:biosynthesis*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D018384:Oxidative Stress; D051381:Rats; D017207:Rats, Sprague-Dawley; D013194:Staining and Labeling; D013482:Superoxide Dismutase / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism; D014018:Tissue Distribution; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000378:metabolism
D013481:Superoxides; D009569:Nitric Oxide; C002744:3-nitrotyrosine; D014443:Tyrosine; D019001:Nitric Oxide Synthase; D013482:Superoxide Dismutase; D009252:NADPH Dehydrogenase