Autometallographic localization of inorganic mercury in the kidneys of rats: effect of unilateral nephrectomy and compensatory renal growth.

The histochemical technique of autometallography was used in the present study to demonstrate the zonal and tubular localization of inorganic mercury in the kidneys of unilaterally nephrectomized (NPX) and sham-operated (SO) rats given either a nontoxic 0.5 mumol/kg or a toxic 2.5 mumol/kg dose of mercuric chloride 10 days after surgery. Deposits were found in the cortex and outer stripe of the outer medulla in both groups of rats given either dose of mercuric chloride. The deposits were localized exclusively in the convoluted and straight portion of the proximal tubule. Forty eight hours after the administration of the 0.5 mumol/kg dose of mercuric chloride, there were significantly more deposits in the renal outer stripe of the NPX rats than in the renal outer stripe of the SO rats. The number of deposits in the renal outer stripe of the NPX and SO rats given the 2.5 mumol/kg dose of mercuric chloride was similar after 24 hr, but was greater than the corresponding rats given the nontoxic dose. These findings suggest that the proximal tubule (particularly the pars recta) is the primary site for the accumulation of inorganic mercury in the kidney. They also suggest that, in the rat, there is enhanced accumulation of inorganic mercury in the pars recta of proximal tubules in the outer stripe of the renal outer medulla when a nontoxic dose of inorganic mercury is given after unilateral nephrectomy or when a toxic dose of mercuric chloride is administered.