[Theophylline and urinary elimination of lithium in the anesthetized dog]

The effect of theophylline (intrarenal perfusion of 1.2 then of 2.4 mg/kg for two successive 15 minute periods) on urinary lithium elimination was studied in 6 pentobarbital anaesthetized dogs perfused with intravenous lithium chloride. Lithium and inulin clearance and the urinary elimination of sodium, potassium and phosphate were studied. Theophylline increases lithium clearance, glomerular filtration and salidiuresis. This salidiuretic effect partly linked to the inhibition of the proximal reabsorption of sodium attested by the rise in phosphate elimination contrasts with the absence of modifications in the fractional tubular reabsorption of lithium. Under our experimental conditions the increased lithium clearance seems linked to the increased glomerular filtration.