THE SUSCEPTIBILITY OF SPONTANEOUSLY DIABETIC MICE TO CADMIUM-METALLOTHIONEIN NEPHROTOXICITY

Cadmium metallothionein (CdMT) was injected subcutaneously into obese hyperglycaemic Umea ob/ob mice or their lean litter mates (normal mice ) at doses of 0, 0.1 and 0.4 mg Cd/kg. Proteinuria and calciuria were induced in both types of mice, but in the ob/ob mice this condition de veloped at a lower dose of CdMT (0.1 mg Cd/kg) than in the normal mice (0.4 mg Cd/kg). These results show, therefore, that Umea ob/ob mice a re particularly susceptible to CdMT-induced nephrotoxicity. The mechan ism underlying this phenomenon needs to be further investigated. After the administration of CdMT, a dose-related increase in glycosuria was observed in both types of mice, in spite of decreased levels of serum insulin and glucose. It is suggested that such glycosuria induced by CdMT could be one of the signs of cadmium nephrotoxicity. The results of the present study thus indicate that metabolic changes like those i n diabetes may increase susceptibility to cadmium-induced renal tubula r damage.