Abstract
The cell-attached patch-clamp configuration has been used to determine the single channel properties of the N-methyl-D-aspartate (NMDA) ion channel with activation of the NMDA receptor by stereoisomer agonists. All of the agonists studied, including the L and d forms of N-methyl-aspartate and the L and d forms of homocysteate, activated a 42-pS conductance channel in cultured hippocampal neurons. For all agonists, the mean open times of the channel were diminished with increased patch hyperpolarization and exhibited an exponential dependence on potential over the range -40 mV to -120 mV. The mean open times, for patch potentials close to resting potential, and the mean frequencies of channel openings, at all patch potentials, were significantly different between each member of the stereoisomer pairs. For both L-homocysteate and NMLA, a fourfold increase in the patch pipette concentration caused an approximate quadrupling in the frequency of unitary events, with no significant change in mean open time. The open channel probability was used as a measure of agonist potency, and, at a concentration of 30 μM, NMDA and L-homocysteate were significantly more potent (P open in excess of 1.5%) than the corresponding stereoisomer compounds NMLA and D-homocysteate (P open near 0.3%). The relative potencies of the stereoisomer pairs were in reasonable agreement with the potency ratios measured in binding studies.
Similar content being viewed by others
References
Ascher P, Bregestovski P, Nowak L (1988) N-methyl-d-aspartate activated channels of mouse central neurones in magnesium-free solutions. J Physiol (Lond) 399:207–226
Banker GA, Cowan WM (1977) Rat hippocampal neurons in dispersed cell culture. Brain Res 126:397–425
Collingridge GL, Lester RAJ (1989) Excitatory amino acid receptors in the vertebrate central nervous system. Pharmacol Rev 40:143–210
Colquhoun D, Ogden DC (1988) Activation of ion channels in the frog end-plate by high concentrations of acetylcholine. J Physiol (Lond) 395:131–159
Colquhoun D, Sakmann B (1985) Fast events in single channel currents activated by acetylcholine and its analogues at the frog muscle end-plate. J Physiol (Lond) 369:501–557
Fagg GE, Baud J (1988) Characterization of NMDA receptor-ionophore complexes in the brain. In: Lodge D (ed) Excitatory amino acids in health and disease. Wiley, New York, pp 63–90
Gibb AJ, Colquhoun D (1991) Glutamate activation of a single NMDA receptor-channel produces a cluster of channel openings. Proc R Soc Lond [Biol] 243:39–45
Howe JR, Colquhoun D, Cull-Candy SG (1988) On the kinetics of large conductance glutamate-receptor ion channels in rat cerebellar granule neurons. Proc R Soc Lond (Biol) 233:407–422
Howe JR, Cull-Candy SG, Colquhoun D (1991) Currents through single glutamate receptor channels in outside-out patches from rat cerebellar granule cells. J Physiol (Lond) 432:143–202
Huettner JE, Bean BP (1988) Block of N-methyl-d-aspartate-activated current by the anticonvulsant MK-801: selective binding to open channels. Proc Natl Acad Sci 85:1307–1311
Jahr CE, Stevens CF (1987) Glutamate activates multiple single channel conductances in hippocampal neurones. Nature 325:522–525
Landman MTR, Albuquerque EX (1989) Ethanol potentiates and blocks NMDA-activated single channel currents in rat hippocampal neurons. FEBS Lett 247:61–67
Lester RAJ, Jahr CE (1992) NMDA channel behavior depends on agonist affinity. J Neurosci 12(2):635–643
Mayer ML, Westbrook GL (1987) Permeation and block of Nmethyl-d-aspartic acid receptor channels by divalent cations in mouse cultured central neurones. J Physiol (Lond) 394:501–527
Mayer ML, Vyklicky L Jr, Clements J (1989) Regulation of NMDA receptor desensitization in mouse hippocampal neurons by glycine. Nature 338:425–427
McLarnon JG, Curry K (1990a) Single channel properties of the N-methyl-scd-aspartate receptor channel using NMDA and NMDA agonists: on-cell recordings. Exp Brain Res 82:82–88
McLarnon JG, Curry K (1990b) Quinolinate activation of Nmethyl-d-aspartate ion channels in rat hippocampal neurons. Neurosci Lett 116:341–346
McLarnon JG, Wong JHP, Sawyer D, Baimbridge KG (1991) The actions of intermediate and long-chain length n-alkanols on unitary NMDA currents in hippocampal neurons. Can J Physiol Pharmacol 69:1422–1427
Mewett KN, Oakes DJ, Olverman HJ, Smith DAS, Watkins JC (1983) Pharmacology of the excitatory actions of sulphonic and sulphinic amino acids. In: Mandel P, De Feudis FV (eds) CNS receptors: from molecular pharmacology to behavior. Raven, New York, pp 163–174
Nowak L, Bregestovski P, Ascher P, Herbet A, Prochiantz A (1984) Magnesium gates glutamate-activated channels in mouse central neurones. Nature 307:462–465
Olverman HJ, Jones AW, Mewett KN, Watkins JC (1988) Structure/ activity relations of N-methyl-d-aspartate receptor ligands as studied by their inhibition of [3H]d-2-amino-5-phosphonopentanoic acid binding in rat brain membranes. Neuroscience 26:17–31
Papke RL, Millhauser G, Lieberman Z, Oswald RE (1988) Relationships of agonist properties to the single channel kinetics of nicotinic acetylcholine receptors. Biophys J 53:1–10
Patneau DK, Mayer ML (1990) Structure-activity relationships for amino acid transmitter candidates acting at N-methyl-scd-aspartate and quisqualate receptors. J Neurosci 10:2385–2399
Peet MJ, Curry K, Magnuson DSK, McLennan H (1987) The Nmethyl-d-aspartate receptor and burst firing of CA1 hippocampal pyramidal neurons. Neuroscience 22:563–571
Sather W, Johnson JW, Henderson G, Ascher P (1990) Glycine-in-sensitive desensitization of NMDA responses in cultured mouse embryonic neurons. Neuron 4:725–731
Wright JM, Nowak LM (1990) Voltage-dependent change in probability of opening (nPo) of N-methyl-scd-aspartate (NMDA) channels in Mg free solutions. Biophys J 57:127a
Zorumski CF, Yang J, Fischbach GD (1989) Calcium-dependent, slow desensitization distinguishes different types of glutamate receptors. Cell Mol Neurobiol 9:95–104
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
McLarnon, J.G., Sawyer, D. Dependence of single channel properties of the N-methyl-d-aspartate ion channel on stereoisomer agonists. Exp Brain Res 95, 8–14 (1993). https://doi.org/10.1007/BF00229649
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00229649