Abstract
Microdissected Deiters' neuron plasma membranes have been used for studying the passage of GABA through the membrane both in the inward and outward direction. Working with 0.2 mM GABA in the compartment simulating the outside of the neurone and with 2.0 mM GABA in the one simulating the inside we found a net transport of GABA towards the inside. This mechanism does not require a Na+ ion gradient across the membrane. The nature of the transport process involved was studied by determining the rate of [3H]-GABA inward passage as a function of GABA concentration (1 nM–800 μM) on the outward side of the membrane. The results have shown that until 50 μM a diffusion process (v=D1×C, where D1=3.1×10−11 1/μm2×sec) is the sole mechanism involved. Above 50 μM a second diffusion process is activated v=D2×(C−50×10−6), where D2=2.8×10−11 1/μm2×sec. Taking in account both inward and outward directed diffusion, one can calculate 16 μM as the equilibrium concentration of GABA on the outward side of the membrane. From a kinetic point of view, these diffusion processes are able to reduce GABA concentration in a synaptic cleft from 3 mM to 20 μM within 3 μ sec. These diffusion systems are discussed as extremely efficient in removing the excess of released GABA in the synaptic cleft.
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Cupello, A., andHyden, H. 1981. On the presence of met5-enkephalin receptors on the plasma membrane of Deiters' neurons and their modulation of GABA transport. J. Neurosci. Res. 6:579–583.
Early, S. L., Michaelis, E. K., andMertes, M. P. 1981. Pharmacological specificity of synaptosomal and synaptic membrane γ-aminobutyric acid (GABA) transport processes. Biochem. Pharmacol. 30:1105–1113.
Hyden, H., Cupello, A., andPalm, A. 1984. Increased binding of GABA to its postsynaptic carrier sites on the plasma membrane of Deiters' neurons after a learning experiment in rats. Brain. Res. 294:37–45.
Hyden, H., andLange, P. W. 1981. The effect of S100 protein on the plasma membrane function of neurons. Cellular and Molec. Neurobiol. 1:313–317.
Hyden, H., Lange, P. W., andLarsson, S. 1980. S-100 glia regulation of GABA transport across the nerve cell membrane. J. of Neurol. Sci. 45:303–316.
Larsson, O. M., Krogsgaard-Larsen, P., andSchousboe, A. 1980. High affinity uptake of (RS)-nipecotic acid in astrocytes cultured from mouse brain. Comparison with GABA transport. J. Neurochem. 34:970–977.
Martin, D. L. 1976. Carrier-mediated transport and removal of GABA from synaptic regions. Pages 347–386,in Roberts, E., Chase, T. N., andTower, D. B. (eds.), GABA in nervous system function. Raven Press, New York.
Okada, Y., andShimada, C. 1976. Gamma-aminobutyric acid (GABA) concentration in a single neuron-localization of GABA in Deiters' neuron. Brain Res. 107:658–662.
Olsen, R. W., andSnowman, A. M. 1982. Chloride-dependent enhancement by barbiturates of GABA receptor binding. J. Neurosci. 2:1812–1823.
Sellstrom, A., Venema, R., andHenn, F. 1976. Functional assessment of GABA uptake or exchange by synaptosomal fractions. Nature 264:652–653.
Study, R. E., andBarker, J. L. 1981. Diazepam and (−)-pentobarbital: fluctuation analysis reveals different mechanisms for potentiation of γ-aminobutyric acid responses in cultured central neurons. Proc. Natl. Acad. Sci. USA 78:7180–7184.
Takeuchi, A., andTakeuchi, N. 1969. A study of the action of picrotoxin on the inhibitory neuromuscolar junction of the crayfish J. Physiol. 205:377–391.
Turner, A. J., andWhittle, S. R. 1983. Biochemical dissection of the γ-aminobutyrate synapse. Biochem. J. 209:29–41.
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Hyden, H., Cupello, A. & Palm, A. Asymmetric diffusion into the postsynaptic neuron: An extremely efficient mechanism for removing excess GABA from synaptic clefts on the Deiters' neurone plasma membrane. Neurochem Res 11, 695–706 (1986). https://doi.org/10.1007/BF00965338
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DOI: https://doi.org/10.1007/BF00965338