Selectivity of food colours for different organic acid transport systems in rat renal cortex

Seventeen food colours were tested as inhibitors of the simultaneous uptake of labelled o-iodohippurate and iodipamide into slices of rat renal cortex. The results have been interpreted in terms of inhibition of two different aniontransport systems: the hippurate of H-system and the liver-like L-system. No clearcut relation was found between inhibition ability and system specificity on the one hand and moleculr weight or structure on the other. However, most disulphonic azo dyes and quinoline yellow show an L-system affinity while tri-and tetra-sulphonic azo dyes, triarylmethanes and erytrosine show very little predilection for either of the two systems.