[Lithium elimination by the isolated perfused rat kidney (author's transl)]

The pharmacokinetics of lithium, a drug with a narrow therapeutic index, depends on the renal elimination of the metal. An open circuit, constant flow isolated rat kidney preparation perfused with gelatinized (Haemaccel) Krebs-solution, was used to study the urinary elimination of lithium relative to sodium. A series of 88 kidney preparations perfused with a solution containing 0.47 mmol/l lithium was compared to another of 52 kidney preparations perfused without lithium. Lithium reduced the tubular reabsorption of sodium but did not modify the elimination of potassium. There is a strong correlation between the tubular reabsorption of lithium and of sodium. The correlation between tubular reabsorption of lithium and filtered load demonstrates the existence of a glomerulo-tubular balance.