A transient urinary acidification was induced in the bullfrog proximal tubule by the peritubular administration of ouabain (10-4M). Insulin (200mIU/ml) provoked a prolonged decrease of tubular fluid pH (TFpH), whereas dibutyryl cyclic AMP (10-4M) produced a transient increase of TFpH. The above data support the view that the urinary acidification in the proximal tubule is not explained by a simple mechanism, such as Na+/H+ exchange.
