beta-Alanine uptake by mouse brain slices.

beta-[3H]Alanine uptake by mouse brain slices was studied in Krebs-Ringer-HEPES-glucose medium (pH 7.4) under O2. The uptake was temperature-sensitive and consisted of two saturable transport components, high- and low-affinity, with kinetic parameters comparable to those of amino acid neurotransmitter candidates. beta-Alanine uptake was strictly sodium-dependent and also inhibited by the omission of potassium and presence of ouabain, suggesting that the transport is mainly fuelled by cation gradients. Sodium ions showed positive cooperative effects in beta-alanine uptake, indicating the association of at least two sodium ions in the transfer of one molecule of beta-alanine. The uptake was strongly inhibited by gamma-aminobutyrate and hypotaurine, the high-affinity uptake component completely disappearing in the presence of hypotaurine. Taurine had no measurable effect. The results suggest that the high-affinity transports of beta-alanine and hypotaurine may be mediated by the same system.