The effect of combined treatment with potassium dichromate and maleic acid on renal function in the rat.

Subthreshold doses of potassium dichromate (K2Cr2O7) have been shown to enhance or potentiate the nephrotoxic effects of mercuric chloride and citrinin. The mechanism of this effect is unknown. The purpose of this study was to examine the phenomenon further by investigating the interaction of K2Cr2O7 with maleic acid, a nephrotoxicant with an action though to be different from those above. Male rats were housed in stainless steel metabolism cages and received a single intraperitoneal injection of maleic acid (300 mg/kg). K2Cr2O7 (10 mg/kg s.c.) or the combination of maleic acid plus K2Cr2O7. While treatment with either agent alone produced only minimal alterations in renal function, the combination of agents produced marked changes in 24 h urine volume, glucose excretion and osmolality. Water consumption was unaffected by the combined treatment. A marked decline in the capacity of renal slices to accumulate both organic anions (p-aminohippurate) and cations (tetraethylammonium) was observed after treatment with both substances. Modifications in renal and hepatic non-protein sulfhydryl content also were observed. These results suggest that K2Cr2O7, as was observed with both mercury and citrinin, enhanced or potentiated the nephrotoxic effects of maleic acid, probably in the proximal tubule, the principal site of glucose reabsorption and organic ion secretion.