Nephrotoxic effects of lead nitrate in Rana ridibunda.

The impact of lead (Pb) on kidney histopathology of the frog Rana ridibunda was investigated. Female frogs were exposed for 4, 10 and 30 days to 14 ppm lead (as lead nitrate). All the lead concentrations and many histological changes were time dependent. Light microscopy of kidney revealed morphological changes mainly in the proximal convoluted tubule (PCT) cells. The most severe changes such as vacuolation, Perl's stained material, infiltration, brush border destruction and proximal tubule damage were detected in the animals exposed for 10 and 30 days. Karyomegaly was highest at 10-days exposure, probably as a result of intense stress caused by the lead. Some PCT in the 30-days-exposed animals were von Kossa's method positive, suggesting the presence of calcium. The possibility is discussed that some of these changes, such as karyomegaly and intranuclear inclusions, might be preneoplastic if lead was supplied at high concentrations and for long time.