The accumulation of [³H]GABA in rat sensory gangliain vitro is exclusively localised within satellite glial cells. Using a GABA concentration of 1 × 10⁻⁷M, the uptake continued linearly for 4 h in the presence of 10 μM amino-oxyacetic acid (AOAA) attaining a tissue/medium ratio of 100:1; in the absence of AOAA the uptake started to saturate after 2 h, the tissue/medium ratio being 25:1.

The uptake appeared to be mediated by a kinetically saturable process with an apparentK_m of 10 μM (high affinity) and was extremely dependent on the presence of external sodium ions.

Drug inhibition studies indicated that the high affinity uptake was not inhibited by the GABA receptor antagonists bicuculline and picrotoxin or by the amino acids glutamate, glycine or glutamine.

Detailed comparison of the inhibition properties of certain GABA analogues and other pharmacological agents revealed direct differences between cortical slices and sensory ganglia.l-2,4-Diaminobutyric acid was 20 times more potent an inhibitor of uptake in cortical slices than in sensory ganglia; conversely β-alanine was 200 times more potent an inhibitor of sensory ganglion uptake. Chlorpromazine andp-chloromercuriphenyl sulphonate were far less potent inhibitors of the ganglia than the cortical slices.

In conclusion the uptake process of glial cells in sensory ganglia shows certain distinct differences from that of cortical neurones. The rate of GABA uptake in the ganglia is much slower than in the cortex. This may result from the low V_max value in the ganglia indicating a sparsity of uptake sites. The ganglion uptake is greatly enhanced in the presence of AOAA implying a rapid catabolism of GABA taken into glial cells by the enzyme GABA: glutamate transaminase. The differences in drug sensitivity indicate that the two active transport systems exhibit different binding sites.