Effect of sodium bicarbonate and ammonium chloride ingestion in experimental gentamicin nephrotoxicity in rats

To examine the possibility that gentamicin binding to renal tubular epithelium is electrostatic, the effect of sodium bicarbonate-induced alkaline diuresis and ammonium chloride administration on the course of gentamicin nephrotoxicity in male Fischer 344 rats was examined. After 14 days of gentamicin, sodium bicarbonate drinking animals did not differ significantly from tap water drinking controls in the degree of nephrotoxicity as determined by serum creatinine, in vitro para-aminohippurate and N-methylnicotinamide uptake, histology and renal cortical gentamicin concentrations. However, 7/10 sodium bicarbonate drinking animals had extensive intratubular renal calcifications as compared to 0/29 tap water drinkers. Ammonium chloride drinking animals had more severe toxicity than tap water drinking controls. We conclude that in our model, sodium bicarbonate administration does not reduce experimental gentamicin toxicity and is associated with intratubular calcification. Ammonium chloride potentiates gentamicin nephrotoxicity.