[Transport of lithium in rat renal cortex slices]

Slices of the renal cortex take up lithium from the incubation medium; this uptake does not follow a saturation kinetics and is demonstrable under aerobic and anaerobic conditions alike. The lithium uptake is associated with a variation of the sodium and potassium content in the slices. These changes are distinguishable from the electrolyte movements caused by the introduction of the slices into the incubation medium. The present findings characterize the lithium uptake into the renal tissue as a passive process. With the in vivo experiments, accumulation of lithium in the renal tissue against the serum should presuppose glomerular filtration and enrichment of lithium in the lumen of the tubuli through processes of urine concentration. In slices of the renal cortex, like in the intact animal the uptake of lithium can be influenced by inhibitors of the renal electrolyte movement. The present findings have provided evidence that lithium enters the tubular cells passively, and that slices of the renal cortex are suited for testing substances acting on the renal handling of lithium.