Parathyroidectomy enhances the nephrotoxicity of gentamicin

Abstract

The objective of this study was to evaluate the effect of parathyroidectomy on the renal function in rats treated with saline (control), low-dose gentamicin (GM, 4 mg/kg per day), or high-dose GM (40 mg/kg per day) for 10 consecutive days. Gentamicin sulfate was dissolved in saline. A group of rats were subjected to thyroparathyroidectomy (PTX) 2 to 3 days before the beginning of the GM treatment. Thyroxine (1 mu g/100 g body weight) was subcutaneously injected daily into PTX rats. in rats with saline infusion, a significant reduction in renal functional variables was obtained after PTX. When GM treatment and PTX were both present, a further impairment in the glomerular filtration rate and the urine/plasma inulin ratio was observed, suggesting additive effects. in rats infused with ammonium chloride to cause metabolic acidosis, a decline in glomerular filtration rate was obtained, a condition that was aggravated when GM treatment and PTX were both present. Acid excretion was significantly reduced in PTX groups, mainly during acidosis. in acidotic PTX rats treated with both low and high GM doses, the excreted amount of acid was strongly impaired, compared with the acidotic non-PTX GM group. These results show that in the PTX rats nephrotoxicity of GM is increased, which suggests that in this experimental model, parathyroid hormone may exert a protective effect during aminoglycoside treatment.