P-AMINOHIPPURATE ACCUMULATION IN KIDNEY CORTEX SLICES - STIMULATION BY DICARBOXYLATES, AMINO-ACIDS AND THEIR OXOANALOGUES

The effect of various amino acids and oxoacids on the accumulation of PAH in rat kidney cortex slices was determined. The following compounds were found to increase the PAH tissue to medium ratio (T/M(PAH)): a) dicarboxylic acids: glutarate, 2-oxoglutarate and oxaloacetate, b) amino acids: glutamate, isoleucine, leucine, valine, methionine, tryptophane, histidine, threonine and glycine, c) monocarboxylates: hydroxymethionine, oxovaline, oxoisoleucine and oxoleucine. There were no marked concentration/effect differences to glycine, glutamate, glutarate and oxovaline. Ouabain inhibited T/M(PAH) only slightly, but abolished its increase by pyruvate, 2-oxoglutarate and histidine. Oxygen hyposaturation abolished the T/M(PAH) increase caused by 2-oxoglutarate, pyruvate, glutamate and histidine. It is concluded that various substrates stimulating the organic anion transport system (OATS) do so namely by improving the energy supply, although the direct participation of dicarboxylates in OATS could be relevance namely in short-lasting variations.