Handling of triamterene by the isolated perfused rat kidney

Quantitative studies on the renal handling of [3H]triamterene were performed in an isolated perfused rat kidney with near normal function and in an isolated kidney with negligible filtration rate, but preserved perfusate flow rate. The excretory pattern for [3H]triamterene is compatible with that of other weak bases such as quinine and quinacrine. Tubular secretion of [3H]triamterene is strongly inhibited by anoxia and iodoacetate. Tubular reabsorption of [3H]triamterene becomes pronounced when the urine is alkaline. Clearances were reported with and without correction for perfusate albumin binding which is about 75%. Bidirectional transport processes are operative in that [3H]triamterene is secreted by the renal tubule and passively diffuses back across the tubular epithelium by a pH-dependent mechanism.