Abstract

Hippuric acid and 33 related substances have been studied in the dog for their manner of renal excretion and their influence on renal tubular transport of p-aminohippurate. Hippuric acid is excreted by the renal tubule and exhibits quantitative competition with p-aminohippurate. Of the related substances, tubular excretion occured only with those containing the carhoxyl and a benzamido or benzimido group. Substituation in the phenyl of the benzamido group may reduce the tubular excretion. Substances with a carboxyl and also a carbonyl-or-imino group but lacking a benzamido or -imido group did not undergo tubular excretion. The spatial separation of the carhoxyl and benzamido groups is not critical for transport until a certain distance is exceeded. Many of the substances found not to undergo tubular excretion had a depressant action on transport of p-aminohippurate.