Effect of acetylsalicylic acid on ionic reabsorption in the renal tubule

Abstract

This study was undertaken to investigate the possibility that ASA (o-acetoxy benzoic acid) could affect the renal tubular reabsorption of ions. Control clearance experiments in dogs were compared to clearances in the same animals during infusion of ortho-substituted congeners of benzoic acid. ASA reduced the excretory rates of Na+, Cl-, Ca++, and Mg++ by about 50%. As there was no effect on GFR [glomerular filtration rate],the effect was attributed to augmentation of the tubular reabsorption of these ions. There was no appreciable effect on K+ excretion. The Na effect probably occurred proximal to the distal K+ secretory site and did not appear to be aldosterone mediated. ASA reduced HCO3- excretion by 45% and increased excretion of titratable acid which suggested augmentation of Na+-H+ exchange in the distal tubule proximal to the K+ secretory site. The effect on reabsorption appeared to be specifically due to the ortho acetoxy substitution on benzoic acid. Ethoxy, acetyl, and hydroxy substitutions did not have this effect. These substitutions increased ionic excretion.