Abstract
Chloride currents were activated by a low concentration of GABA (0.5 μ m) in neonatal rat hippocampal neurons cultured for up to 14 days. Currents elicited by 0.5 μ m GABA in neurons, voltage-clamped using the whole-cell technique with pipettes containing 149 mm Cl−, reversed close to 0 mV whether pipettes contained 144 mm Na+ or 140 mm Cs+, and were blocked by 100 μ m bicuculline. Current-voltage curves showed outward rectification. Single channel currents appeared in cell-attached patches when the pipette tip was perfused with pipette solution containing 0.5 μ m GABA and disappeared when a solution containing 100 μ m bicuculline plus 0.5 μ m GABA was injected into the pipette tip. The channels showed outward rectification and, in some patches, had a much lower probability of opening at hyperpolarized potentials. The average chord conductance in 10 patches hyperpolarized by 80 mV was 7.8±1.6 pS (sem) compared with a chord conductance of 34.1±3.5 pS (sem) in the same patches depolarized by 80 mV. Similar single channel currents were also activated in cell-free, inside-out patches in symmetrical chloride solutions when 0.5 μ m GABA was injected into the pipette tip. The channels showed outward rectification similar to that seen in cell-attached patches, and some channels had a lower probability of opening at hyperpolarized potentials. The average chord conductance in 13 patches hyperpolarized by 80 mV was 11.8±2.3 pS (sem) compared with 42.1±3.1 pS (sem) in the same patches depolarized by 80 mV.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Allen, C.N., Albuquerque, E.X. 1987. Conductance properties of GABA-activated chloride currents recorded from cultured hippocampal neurons. Brain Res. 410:159–163
Barker, J.L., Harrison, N.L. 1988. Outward rectification of inhibitory postsynaptic currents in cultured rat hippocampal neurones. J. Physiol. 403:41–55
Blair, L.A.C., Levitan, E.S., Marshall, J., Dionne, V.E., Barnard, E.A. 1988. Single subunits of the GABAA receptor form ion channels with properties of the native receptor. Science 242:577–579
Bormann, J., Hamill, O.P., Sakmann, B. 1987. Mechanism of anion permeation through channels gated by glycine and gamma-aminobutyric acid in mouse cultured spinal neurones. J. Physiol. 385:243–286
Bormann, J., Kettenmann, H. 1988. Patch-clamp study of gamma-aminobutyric acid receptor Cl− channels in cultured astrocytes. Proc. Natl. Acad. Sci. USA 85:9336–9340
Collingridge, G.L., Gage, P.W., Robertson, B. 1984. Inhibitory postsynaptic currents in rat hippocampal CA1 neurones. J. Physiol. 356:551–564
Fatima-Shad, K., Barry, P.H. 1992. A patch-clamp study of GABA- and strychnine-sensitive glycine-activated currents in post-natal tissue-cultured hippocampal neurons. Proc. R. Soc. Lond. [Biol.] 250:99–105
Goldman, D.E. 1943. Potential, impedance, and rectification in membranes. J. Gen. Physiol. 27:37–60
Gray, R., Johnston, D. 1985. Rectification of single GABA-gated chloride channels in adult hippocampal neurons. J. Neurophysiol. 54:134–142
Hales, T.G., Lambert, J.J. 1991. The actions of propofol on inhibitory amino acid receptors of bovine adrenomedullary chromaffin cells and rodent central neurones. Br. J. Pharmacol. 104:619–628
Hamill, O.P., Bormann, J., Sakmann, B. 1983. Activation of multiple-conductance state chloride channels in spinal neurones by glycine and GABA. Nature 305:805–808
Hodgkin, A.L., Katz, B. 1949. The effect of sodium ions on the electrical activity of the giant axon of the squid. J. Physiol. 108:37–77
Huck, S., Lux, H.D. 1987. Patch-clamp study of ion channels activated by GABA and glycine in cultured cerebellar neurons of the mouse. Neurosci. Lett. 79:103–107
Krouse, M.E., Schneider, G.T., Gage, P.W. 1986. A large anion-selective channel has seven conductance levels. Nature 319:58–60
Levitan, E.S., Blair, L.A.C., Dionne, V.E., Barnard, E.A. 1988a. Biophysical and pharmacological properties of cloned GABAA receptor subunits expressed in Xenopus oocytes. Neuron 1:773–781
Levitan, E.S., Schofield, P.R., Burt, D.R., Rhee, L.M., Wisden, W., Kohler, M., Fujita, N., Rodriguez, H.F., Stephenson, A., Darlison, M.G., Barnard, E.A., Seeburg, P.H. 1988b. Structural and functional basis for GABAA receptor heterogeneity. Nature 335:76–79
MacDonald, R.L., Rogers, C.J., Twyman, R.E. 1989. Kinetic properties of the GABAA receptor main conductance state of mouse spinal cord neurones in culture. J. Physiol. 410:479–499
Mathers D.A. 1991. Activation and inactivation of the GABAA receptor: insights from comparison of native and recombinant subunit assemblies. Can. J. Physiol. Pharmacol. 69:1057–1063
Miller, C. 1982. Open-state substructure of single chloride channels from Torpedo electroplax. Philos. Trans. R. Soc. London, B 299:401–411
Olsen, R.W., Tobin, A.J. 1990. Molecular biology of GABAA receptors. FASEB J. 4:1469–1479
Peters, J.A., Lambert, J.J., Cottrell, G.A. 1989. An electrophysiological investigation of the characteristics and function of GABAA receptors on bovine adrenomedullary chromaffin cells. Pfluegers Arch. 415:95–103
Premkumar, L.S., Chung, S.-H., Gage, P.W. 1990. GABA-induced potassium channels in cultured neurons. Proc. R. Soc. Lond. [Biol.] 241:153–158
Seeburg, P.H., Wisden, W., Verdoorn, T.A., Pritchett, D.B., Werner, P., Herb, A., Lüddens, H., Sprengel, R., Sakmann, B. 1990. The GABAA receptor family: Molecular and functional diversity. Cold Spring Harbor Symp. Quant. Biol. 55:29–40
Verdoorn, T.A., Draguhn, A., Ymer, S., Seeburg, P.H., Sakmann, B. 1990. Functional properties of recombinant rat GABAA receptors depend upon subunit composition. Neuron 4:919–928
Weiss D.S. 1988. Membrane potential modulates the activation of GABA-gated channels. J. Neurophysiol. 59:514–527
Weiss, D.S., Barnes, J., Hablitz, J.J. 1988. Whole-cell and singlechannel recordings of GABA-gated currents in cultured chick cerebral neurons. J. Neurophysiol. 59:495–513
Yasui, S., Ishizuka, S., Akaike, N. 1985. GABA activates different types of chloride-conducting receptor-ionophore complexes in a dose-dependent manner. Brain Res. 344:176–180
Author information
Authors and Affiliations
Additional information
We are grateful to B. McLachlan and M. Robertson for their general assistance, to C. McCulloch and M. Smith for writing computer programs and to W. O'Hare for making the pipette injection device.
Rights and permissions
About this article
Cite this article
Curmi, J.P., Premkumar, L.S., Birnir, B. et al. The influence of membrane potential on chloride channels activated by GABA in rat cultured hippocampal neurons. J. Membarin Biol. 136, 273–280 (1993). https://doi.org/10.1007/BF00233666
Received:
Revised:
Issue Date:
DOI: https://doi.org/10.1007/BF00233666