Effect of renal fuels on p-aminohippurate transport in rat renal cortical fragments.

The effects of the major renal fuels were studied, i.e., lactate, citrate, palmitate, glutamine, and glucose, at concentrations near those found circulating on the in vitro accumulation of p-aminohippurate (PAH) by rat renal cortical fragments. Only lactate and citrate were found to increase PAH uptake significantly. Noting that 10% v/v normal rat sera enhance PAH accumulation, we studied the renal fuels at 10% circulating concentrations and found that all fuels combined had stimulation comparable to 10% v/v sera. Lactate and the stimulator in normal sera are located in the same Sephadex G-25 fraction of sera. Both lactate, the major renal fuel, and normal sera stimulate the influx and inhibit the efflux of PAH. We conclude that the stimulators to PAH transport in normal sera are, at least in part, renal fuel organic anions.