title: Pyruvate attenuates myoglobin in vitro toxicity.
abstract: Myoglobinuria is a complication of crush injury as well as substance abuse. This study examined whether pyruvate modified myoglobin in vitro renal toxicity. Renal slices from Fischer-344 rats were incubated for 120 min with 0-12 mg/ml myoglobin. In an initial study, gluconeogenesis was stimulated by the addition of 10 mM pyruvate during the final 30 min. In all other studies, renal slices were incubated with myoglobin in the presence of 0 or 10 mM pyruvate for 120 min. Myoglobin increased lactate dehydrogenase (LDH) release and this was not modified by the presence of pyruvate for the last 30 min of the incubation. Myoglobin toxicity was reduced by coincubation of myoglobin with pyruvate for 120 min. LDH leakage was increased 1.2-, 1.7-, and 1.8-fold above control by 4, 10, and 12 mg/ml myoglobin, compared to 1.2, 1.3, and 1.3 fold in slices coincubated with 10 mM pyruvate, respectively. Myoglobin diminished adenosine triphosphate (ATP) levels but pyruvate maintained a 5x higher level of ATP within the slices. Glucose (10 mM) provided protection only for the low concentration (4 mg/ml) of myoglobin. Myoglobin induced oxidative stress while pyruvate prevented the rise in lipid peroxidation and glutathione disulfides by myoglobin. Myoglobin diminished total glutathione levels in pyruvate-treated tissue, but glutathione levels remained higher than tissues incubated in the absence of pyruvate. These results indicate that pyruvate reduced toxicity by preventing oxidative stress and via a supply of an energy substrate.
authors.affiliation: Department of Pharmacology, Marshall University School of Medicine, 1542 Spring Valley Drive, Huntington, West Virginia 25704-9388, USA. alentov@marshall.edu
authors.forename: Monica A
authors.initials: MA
authors.lastname: Valentovic
authors.forename: Jennifer
authors.initials: J
authors.lastname: Minigh
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004336:Drug Antagonism; D005943:Gluconeogenesis / Q000187:drug effects*; D005947:Glucose / Q000494:pharmacology; D019803:Glutathione Disulfide / Q000378:metabolism; D007672:Kidney Cortex / Q000187:drug effects* / Q000378:metabolism; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D015227:Lipid Peroxidation / Q000187:drug effects; D009211:Myoglobin / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D009924:Organ Culture Techniques; D018384:Oxidative Stress / Q000187:drug effects; D019289:Pyruvic Acid / Q000494:pharmacology*; D051381:Rats; D011916:Rats, Inbred F344
chemical_list: D009211:Myoglobin; D019289:Pyruvic Acid; D000255:Adenosine Triphosphate; D007770:L-Lactate Dehydrogenase; D005947:Glucose; D019803:Glutathione Disulfide