Chronic renal lesions in the uninephrectomized Gunn rat after analgesic mixtures.

Chronic cortical and medullary damage have been produced in uninephrectomized homozygous Gunn rats by single doses of the analgesics aspirin, paracetamol and phenazone, and by analgesic mixtures. The lesions are more severe than those of other experimental models of analgesic nephropathy, and the appearances of the cortical lesions suggest that they are ultimately due to the effects of papillary necrosis rather than to acute tubular necrosis observed in acute experiments with this model. The presence of an acute inflammatory reaction in both cortex and medulla in a number of animals one month after administration of analgesics indicates the possibility that the observed chronic renal damage may result from the intervention of additional complicating factors rather than from a single direct effect of analgesics.