Effect of gamma-aminobutyric acid on the carnitine metabolism in neural cells.

Isolated rat cerebral cortex cells were able to accumulate L-carnitine and this process was competitively inhibited by 1 mM gamma-aminobutyric acid (GABA) with a shift of Km from 7.8 +/- 1.9 mM to 14.6 +/- 4.0 mM. Addition of GABA also affected distribution of carnitine derivatives. The decrease of acetylcarnitine level by 1.6 fold was correlated with the inhibition of carnitine acetyltransferase (1.77 times). A postulated involvement of this enzyme in delivering acetyl moieties for acetylcholine synthesis would suggest a negative feedback between GABA and the level of acetylcholine.