[Effect of lithium on the renal excretory function and Na, K-ATPase activity in rats]

Single administration per os of the 0.066 M LiCl solution (3 ml per 100 g body weight) caused natriuresis. In the "lithium" rats with prolonged lithium treatment (i.p. injections during 10 days), polyuria developed; after water or 0.9% NaCl load excretion of Na, K, Ca, Mg and water increased as compared to the control rats. The saluretic effect was very obvious after 0.9% NaCl load in the "lithium" rats. The Na, K ATPase activity was measured by the quantitative cytochemical method, decreased only in the collecting ducts of the "lithium" rats. The natriuretic effect of acute lithium administration seems to be due to a lowering of the sodium proximal reabsorption. Prolonged lithium treatment suppresses the sodium transport in the collecting ducts.