Tags

Type your tag names separated by a space and hit enter

Patch clamp analysis of excitatory synaptic currents in granule cells of rat hippocampus.
J Physiol. 1991 Apr; 435:275-93.JP

Abstract

1. Excitatory postsynaptic potentials (EPSPs) and their underlying currents (EPSCs) were recorded from dentate granule cells in thin hippocampal slices of rats using the tight-seal whole-cell recording technique. 2. At resting membrane potentials (ca -60 to -70 mV), the EPSCs clearly consisted of a dominant fast and a smaller slow component. The slow EPSC component markedly increased with depolarization. This resulted in a region of negative slope conductance (between -50 and -30 mV) in the peak current-voltage (I-V) relation of the dual-component EPSC in most neurones. The EPSCs reversed entirely at -1.2 +/- 2.8 mV (n = 15). 3. Using selective antagonists of N-methyl-D-aspartate (NMDA) and non-NMDA excitatory amino acid receptors, two pharmacologically distinct components of the natural EPSCs were isolated. The non-NMDA EPSCs displayed a linear I-V relation. Their rise times (0.5-1.9 ms) were independent of membrane voltage but seemed to depend critically on the precise dendritic location of the synapse. Their decay was approximated by a single exponential with a time constant ranging from 3 to 9 ms. The time course of these EPSCs was independent of changes in extracellular Mg2+. 4. The NMDA EPSCs displayed a non-linear I-V relation. At resting membrane potentials their peak amplitudes were 20 pA and increased steadily with depolarization to -30 mV. At membrane voltages positive to -30 mV the peak I-V relation was linear. The rise times of NMDA EPSCs ranged from 4 to 9 ms and were insensitive to membrane voltage. 5. The NMDA EPSCs decayed biexponentially. Both time constants, tau f and tau s, increased with depolarization in an exponential manner, tau s being more voltage dependent than tau f. Lowering extracellular Mg2+ slightly reduced both rate constants but did not completely abolish their voltage sensitivity. 6. Bath application of NMDA to outside-out patches from granule cells induced single channel currents of 52 pS in nominally Mg(2+)-free solutions. They displayed a burst-like single-channel activity with clusters of bursts lasting several hundreds of milliseconds. Currents through single NMDA receptor channels reversed around 0 mV. 7. The fractional contributions of NMDA and non-NMDA components to peak currents and synaptic charge transfer were assessed. At resting membrane potential the NMDA EPSC component accounted for 23% of the peak current and for 64% of the synaptic charge transfer. The contribution of the NMDA EPSC component to the synaptic charge transfer strongly increased with small depolarizations from rest.

Authors+Show Affiliations

Max-Planck-Institut für biophysikalische Chemie, Göttingen, Germany.No affiliation info availableNo affiliation info available

Pub Type(s)

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

Language

eng

PubMed ID

1837562

Citation

Keller, B U., et al. "Patch Clamp Analysis of Excitatory Synaptic Currents in Granule Cells of Rat Hippocampus." The Journal of Physiology, vol. 435, 1991, pp. 275-93.
Keller BU, Konnerth A, Yaari Y. Patch clamp analysis of excitatory synaptic currents in granule cells of rat hippocampus. J Physiol. 1991;435:275-93.
Keller, B. U., Konnerth, A., & Yaari, Y. (1991). Patch clamp analysis of excitatory synaptic currents in granule cells of rat hippocampus. The Journal of Physiology, 435, 275-93.
Keller BU, Konnerth A, Yaari Y. Patch Clamp Analysis of Excitatory Synaptic Currents in Granule Cells of Rat Hippocampus. J Physiol. 1991;435:275-93. PubMed PMID: 1837562.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Patch clamp analysis of excitatory synaptic currents in granule cells of rat hippocampus. AU - Keller,B U, AU - Konnerth,A, AU - Yaari,Y, PY - 1991/4/1/pubmed PY - 1991/4/1/medline PY - 1991/4/1/entrez SP - 275 EP - 93 JF - The Journal of physiology JO - J Physiol VL - 435 N2 - 1. Excitatory postsynaptic potentials (EPSPs) and their underlying currents (EPSCs) were recorded from dentate granule cells in thin hippocampal slices of rats using the tight-seal whole-cell recording technique. 2. At resting membrane potentials (ca -60 to -70 mV), the EPSCs clearly consisted of a dominant fast and a smaller slow component. The slow EPSC component markedly increased with depolarization. This resulted in a region of negative slope conductance (between -50 and -30 mV) in the peak current-voltage (I-V) relation of the dual-component EPSC in most neurones. The EPSCs reversed entirely at -1.2 +/- 2.8 mV (n = 15). 3. Using selective antagonists of N-methyl-D-aspartate (NMDA) and non-NMDA excitatory amino acid receptors, two pharmacologically distinct components of the natural EPSCs were isolated. The non-NMDA EPSCs displayed a linear I-V relation. Their rise times (0.5-1.9 ms) were independent of membrane voltage but seemed to depend critically on the precise dendritic location of the synapse. Their decay was approximated by a single exponential with a time constant ranging from 3 to 9 ms. The time course of these EPSCs was independent of changes in extracellular Mg2+. 4. The NMDA EPSCs displayed a non-linear I-V relation. At resting membrane potentials their peak amplitudes were 20 pA and increased steadily with depolarization to -30 mV. At membrane voltages positive to -30 mV the peak I-V relation was linear. The rise times of NMDA EPSCs ranged from 4 to 9 ms and were insensitive to membrane voltage. 5. The NMDA EPSCs decayed biexponentially. Both time constants, tau f and tau s, increased with depolarization in an exponential manner, tau s being more voltage dependent than tau f. Lowering extracellular Mg2+ slightly reduced both rate constants but did not completely abolish their voltage sensitivity. 6. Bath application of NMDA to outside-out patches from granule cells induced single channel currents of 52 pS in nominally Mg(2+)-free solutions. They displayed a burst-like single-channel activity with clusters of bursts lasting several hundreds of milliseconds. Currents through single NMDA receptor channels reversed around 0 mV. 7. The fractional contributions of NMDA and non-NMDA components to peak currents and synaptic charge transfer were assessed. At resting membrane potential the NMDA EPSC component accounted for 23% of the peak current and for 64% of the synaptic charge transfer. The contribution of the NMDA EPSC component to the synaptic charge transfer strongly increased with small depolarizations from rest. SN - 0022-3751 UR - https://www.unboundmedicine.com/medline/citation/1837562/Patch_clamp_analysis_of_excitatory_synaptic_currents_in_granule_cells_of_rat_hippocampus_ L2 - https://onlinelibrary.wiley.com/resolve/openurl?genre=article&sid=nlm:pubmed&issn=0022-3751&date=1991&volume=435&spage=275 DB - PRIME DP - Unbound Medicine ER -