INFLUENCE OF NEUROGLIAL TRANSPORT ON THE ACTION OF γ‐AMINOBUTYRIC ACID ON MAMMALIAN GANGLION CELLS

Abstract

1The effect of inhibiting the transport of γ-aminobutyric acid (GABA) by neuroglial cells on the depolarizing action of exogenous amino acids on isolated superior cervical ganglia of the rat was studied. 2Transport (measured by uptake of [³H]-GABA) was inhibited by (a) reducing external [Na⁺] from 143 to 2 mm and (b) administering alternative carrier-substrates, 3-amino-n-butyric acid (β-amino-butyric acid, BABA) and (±)-nipecotic acid at a concentration of 1 mm. 3All three procedures enhanced the depolarization produced by low concentrations of GABA (<10 μm) but did not alter the maximum response, nor the response to 3-aminopropanesulphonic acid (a gabamimetic with low affinity for the neuroglial carrier). 4It is concluded that the neuroglial uptake process can limit the action of exogenous GABA upon neurones, by reducing the interstitial GABA concentration.