Efflux and exchange of γ-aminobutyric acid and nipecotic acid catalysed by synaptic plasma membrane vesicles isolated from immature rat brain

Two pharmacologically distinct sodium- and chloride-coupled high-affinity gamma-aminobutyric acid transporters are present in plasma membrane vesicles and reconstituted preparations from rat brain.

“…At 5 uM labeled GABA transport is 65% inhibited and at 50 /LM it is fully suppressed. This is in accord with the previously published values for Km of 2-4 gM (7,19,21). Although either ofthe two analogues gives only a partial inhibition, when both of them are added together a single phase of inhibitionessentially going to completion-is observed (Fig.…”

Identification of γ-aminobutyric acid transporter (GAT1) on the rat sperm

“…This observation was in agreement with the result of immunohistochemical staining shown in Fig 3. Since only the elongated spermatids and spermatozoa in testis express GAT1 protein, it is evident that the difference of the staining intensity between lane 2 and 3 in Fig 1 is due to their difference in the relative GAT1 content in protein extracts. The existence of GAT1 can lead to the membrane depolarization which has been demonstrated by other studies [19], [20]. Meanwhile, membrane depolarization is also important for the initiation of the sperm AR [21], so we postulate a possible role of GAT1 in sperm AR.…”

Co-release of acetylcholine and gamma-aminobutyric acid by a retinal neuron.

“…From a mechanistic point of view, the dissociation of acetylcholine and GABA release suggested they are mediated by different mechanisms. An obvious candidate for the Ca2+-independent mechanism was the carrier present in many neurons (32)(33)(34) and thought to mediate intercellular signaling by horizontal cells in fish and amphibians (15)(16)(17)35). Ouabain has been reported to increase the release of GABA from inner retinal neurons, consistent with the existence of a carrier there (36).…”

“…A possible explanation is that GABA is in fact released following stimulation by light, but the change in the rate of GABA release is small compared to the change in release of acetylcholine. Ifthe release ofGABA is mediated by the known GABA carrier, its efflux occurs by electrogenic cotransport with Na+ (15,(32)(33)(34). In that case, depolarization of the cell must tend to drive GABA out through the carrier, and that is what under extreme conditions we observed: K+-induced depolarization increased the release of GABA.…”