Lithium-induced morphological changes in the rat kidney at different levels of urine flow.

Lithium treated rats become polyuric and at the same time develop pronounced dilatations of distal tubular segments and characteristics enzyme histochemical changes. In the present study we have compared lithium-polyuric Wistar rats with lithium treated rats in which the polyuria was prevented either by administration of a vasopressin analogue or by water restriction. The kidneys were studied using enzyme histochemistry and light microscope morphometry. The characteristic lithium induced changes were present in all groups irrespective of the presence or absence of polyuria. It is concluded therefore, that the morphological and enzyme histochemical changes are induced by the lithium ion per se and not by the accompanying polyuria.