Absorption of Organic Anions from the Rat Small Intestine

Abstract

1. Hippuric acid, sulphanilic acid, p-aminohippuric acid, and phenol red, highly ionized compounds of very low lipoid solubilities, were absorbed from the rat small intestine at rates which varied over a 25-fold range.2. Absorption rates ranked in the same order as the chloroform-to-water partition coefficients of the compounds but not in the order of the molecular weights or degrees of ionization.3. The results suggested that these anions are absorbed mainly by simple diffusion through lipoid regions of the intestinal boundary.