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Effects of ammonium ions on synaptic transmission and on responses to quisqualate and N-methyl-D-aspartate in hippocampal CA1 pyramidal neurons in vitro.
Brain Res. 1993 Dec 31; 632(1-2):225-31.BR

Abstract

Effects of NH4Cl on CA1 pyramidal neurons and synaptic transmission were investigated with intracellular recording in fully submerged rat hippocampal slices. Superfusion with 1-4 mM NH4Cl reversibly depolarized the membrane by 15.1 +/- 1.4 mV, reduced the amplitude and broadened the duration of action potentials due to a slower rate of repolarization, without significant change in membrane conductance. When membrane potential was returned to control level by the injection of a steady outward current, action potential amplitude recovered but repolarization remained slow. The extent of depolarization was not dependent on the concentration of NH4Cl between 1 and 4 mM. NH4Cl greatly depressed orthodromic transmission evoked by the stimulation of Schaffer collateral/commissural fibers several minutes after depolarizing the CA1 neuron. Interruption of transmission began with a decrease in excitatory postsynaptic potential (EPSP) amplitude and eventually EPSPs were almost eliminated. When NH4Cl was removed, it took 2-3 min for membrane potential and 10-15 min for transmission to recover. Inward currents induced by bath application of quisqualate acting on alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors were also depressed. In contrast, NH4Cl enhanced N-methyl-D-aspartate (NMDA)-induced currents. This potentiation disappeared in the absence of added Mg2+. A reduction in quisqualate-induced responses provided a possible explanation for the inhibition of excitatory transmission by NH4Cl.

Authors+Show Affiliations

Department of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada.No affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

7908597

Citation

Fan, P, and J C. Szerb. "Effects of Ammonium Ions On Synaptic Transmission and On Responses to Quisqualate and N-methyl-D-aspartate in Hippocampal CA1 Pyramidal Neurons in Vitro." Brain Research, vol. 632, no. 1-2, 1993, pp. 225-31.
Fan P, Szerb JC. Effects of ammonium ions on synaptic transmission and on responses to quisqualate and N-methyl-D-aspartate in hippocampal CA1 pyramidal neurons in vitro. Brain Res. 1993;632(1-2):225-31.
Fan, P., & Szerb, J. C. (1993). Effects of ammonium ions on synaptic transmission and on responses to quisqualate and N-methyl-D-aspartate in hippocampal CA1 pyramidal neurons in vitro. Brain Research, 632(1-2), 225-31.
Fan P, Szerb JC. Effects of Ammonium Ions On Synaptic Transmission and On Responses to Quisqualate and N-methyl-D-aspartate in Hippocampal CA1 Pyramidal Neurons in Vitro. Brain Res. 1993 Dec 31;632(1-2):225-31. PubMed PMID: 7908597.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Effects of ammonium ions on synaptic transmission and on responses to quisqualate and N-methyl-D-aspartate in hippocampal CA1 pyramidal neurons in vitro. AU - Fan,P, AU - Szerb,J C, PY - 1993/12/31/pubmed PY - 1993/12/31/medline PY - 1993/12/31/entrez SP - 225 EP - 31 JF - Brain research JO - Brain Res VL - 632 IS - 1-2 N2 - Effects of NH4Cl on CA1 pyramidal neurons and synaptic transmission were investigated with intracellular recording in fully submerged rat hippocampal slices. Superfusion with 1-4 mM NH4Cl reversibly depolarized the membrane by 15.1 +/- 1.4 mV, reduced the amplitude and broadened the duration of action potentials due to a slower rate of repolarization, without significant change in membrane conductance. When membrane potential was returned to control level by the injection of a steady outward current, action potential amplitude recovered but repolarization remained slow. The extent of depolarization was not dependent on the concentration of NH4Cl between 1 and 4 mM. NH4Cl greatly depressed orthodromic transmission evoked by the stimulation of Schaffer collateral/commissural fibers several minutes after depolarizing the CA1 neuron. Interruption of transmission began with a decrease in excitatory postsynaptic potential (EPSP) amplitude and eventually EPSPs were almost eliminated. When NH4Cl was removed, it took 2-3 min for membrane potential and 10-15 min for transmission to recover. Inward currents induced by bath application of quisqualate acting on alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors were also depressed. In contrast, NH4Cl enhanced N-methyl-D-aspartate (NMDA)-induced currents. This potentiation disappeared in the absence of added Mg2+. A reduction in quisqualate-induced responses provided a possible explanation for the inhibition of excitatory transmission by NH4Cl. SN - 0006-8993 UR - https://www.unboundmedicine.com/medline/citation/7908597/Effects_of_ammonium_ions_on_synaptic_transmission_and_on_responses_to_quisqualate_and_N_methyl_D_aspartate_in_hippocampal_CA1_pyramidal_neurons_in_vitro_ L2 - https://linkinghub.elsevier.com/retrieve/pii/0006-8993(93)91157-N DB - PRIME DP - Unbound Medicine ER -