Amino acid transport in peripheral nerve: specificity of uptake.

Abstract

Abstract—Amino acid uptake has been studied in desheathed frog sciatic nerve. Results indicate that at least two types of processes are involved: a non‐saturable process, possibly simple diffusion, and a saturable, carrier‐mediated process. There appear to be several carrier‐mediated transport mechanisms, which can be separated on the basis of their substrate specificity as follows: small neutral, large neutral, β‐alanine, acidic, basic, aromatic and heterocyclic, and proline. The specificity of some of the mechanisms is incomplete and these can transport certain amino acids from other groups to a limited extent. The percentage of total uptake by a saturable process is highly variable. Basic, acidic, and those amino acids containing aromatic or heterocyclic ring structures are taken up primarily by a saturable process; small and large neutral amino acids and proline are taken up primarily by a non‐saturable process.