The effect of delta-aminolaevulinic acid on the high affinity uptake of aspartic acid by rat brain synaptosomes.

delta-Aminolaevulinic (delta-ALA) acid is an analogue of GABA, glutamate and aspartate. High affinity GABA uptake by synaptosomes is inhibited by delta-ALA in a competitive fashion at high concentrations (greater than 0.5 mM). Glutamate uptake is inhibited in a non-competitive fashion at all delta-ALA concentrations (0.05-2.0 mM). High affinity aspartate uptake is inhibited in a non-competitive fashion at high concentration (greater than 1.0 mM) but exhibits a curve which resembles that for the inhibition of GABA uptake. The different interactions between delta-ALA, glutamate and aspartate may be evidence for a separate transport system for aspartate.