A study of the probenecid effect on amino acid accumulation in kidney cortex slices.

The amount of amino acids accumulated by rat and mouse kidney cortex slices is determined by both membrane transport and intracellular metabolism, especially protein incorporation. Even with substrate concentrations of 100 microM up to 70% of the transported amino acids were found to be protein incorporated. Probenecid reduces the accumulation of the amino acids glycine, L-phenylalanine, L-valine, L-arginine, L-lysine, L-proline and alpha-AIB. At substrate concentrations of 100 microM the inhibition is between 28 and 66% (except alpha-AIB) with a probenecid concentration of 7.0 mM. Slight inhibitory effects were observed with 0.7 mM probenecid. The probenecid effect, however, is mainly on the protein incorporation. With 7.0 mM probenecid protein incorporation is reduced considerably, for some amino acids below 10% of the control values; small inhibitory effects were observed with concentrations of 0.7 mM. Amino acid transport is affected only slightly by probenecid. In consequence, higher accumulation rates of free amino acids may be measured after probenecid administration, preferentially with amino acids showing high initial incorporation rates.