Abstract
Renal toxicity is a common manifestation to the exposure of laboratory animals and humans to a wide range of xenobiotics. Traditional methods for evaluating renal damage by clinical chemistry such as blood urea nitrogen (BUN) and serum creatinine are not sensitive to early, mild changes. The use of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) to measure the molecular weight spectrum of urinary proteins allows for an evaluation of the functional changes associated with renal damage. The ability of the kidney to filter and reabsorb proteins is related to the functional ability of glomeruli and the proximal tubules. Gentamicin sulfate produces injury to the S-1 and S-2 segments of the proximal tubule in laboratory animals and humans. While severe damage to the tubules is associated with increased BUN, serum creatinine, and N-acetyl-β-glucosiminadase (NAG), mild injury is not detected by these means. The evaluation of urinary proteins by SDS-PAGE demonstrated renal toxicity at a dose of 6 mg/kg after 2 days of sc treatment. The NAG: creatinine ratio was shown to be elevated after 2 days of treatment at 63 mg/kg. The use of SDS-PAGE as described in this paper provides a sensitive method for detecting renal injury.