| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Spontaneous synaptic currents were recorded in voltage-clamped CA1 neurones in rat hippocampal slices at room temperature (21-25 degrees C). The currents, which could be seen at the resting membrane potential only when cells were loaded with chloride ions, were blocked by bicuculline. It was concluded that they were inhibitory post-synaptic currents (i.p.s.c.s) generated by the opening of chloride-selective channels activated by gamma-aminobutyric acid (GABA). In twenty-nine cells, ten to forty-five i.p.s.c.s were recorded at a potential between -75 and -85 mV. In every cell, i.p.s.c.s varied widely in amplitude with an average coefficient of variation of 28.7%. The mean amplitude varied from 0.22 to 1.16 nA with an average of 0.52 nA. Reversed (outward) currents could be recorded from cells voltage clamped at positive potentials. Null potentials varied between -20 and +20 mV, the variability being attributed to differences in chloride loading. Most currents had a rapid growth phase with a mean growth time (20-80% of peak) of 1.1 ms followed by a slower decay phase. The decay phase was exponential with a single time constant. The average decay time constant (tau D) ranged from 8.3 to 16.2 ms with a mean value of 11.0 ms. The rate of decay of currents was affected by membrane potential. tau D decreased exponentially with hyperpolarization in the range from +40 to -120 mV with an average volt constant (H value) of 146 +/- 9.6 mV (mean +/- 1 S.E. of mean, n = 17). The mean value of tau D at 0 mV was 19 ms. In some cells, growth times also decreased with hyperpolarization. The decay of currents was faster at higher temperatures but remained exponential. At 32 degrees C, the average tau D at 0 mV was 8.3 ms (n = 5) giving a Q10 value of 3.3 for the decay time constant at 0 mV. The frequency and mean amplitude of i.p.s.c.s were reduced by tetrodotoxin (TTX) or cadmium, indicating that many of the currents were generated by action potentials in presynaptic terminals. The spontaneous 'miniatures' remaining had the same time course and voltage sensitivity as currents recorded in normal solutions. Pentobarbitone (50-100 microM) greatly prolonged the decay of i.p.s.c.s but had no discernible effect on their amplitude or growth phase.
This article has been cited by other articles:
|
|
 |
|
  E. A. Mitchell, L. J. Gentet, J. Dempster, and D. Belelli GABAA and glycine receptor-mediated transmission in rat lamina II neurones: relevance to the analgesic actions of neuroactive steroids J. Physiol., September 15, 2007; 583(3): 1021 - 1040. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. B. Hardie and R. A. Pearce Active and Passive Membrane Properties and Intrinsic Kinetics Shape Synaptic Inhibition in Hippocampal CA1 Pyramidal Neurons. J. Neurosci., August 15, 2006; 26(33): 8559 - 8569. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 V. Santhakumar, I. Aradi, and I. Soltesz Role of Mossy Fiber Sprouting and Mossy Cell Loss in Hyperexcitability: A Network Model of the Dentate Gyrus Incorporating Cell Types and Axonal Topography J Neurophysiol, January 1, 2005; 93(1): 437 - 453. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. Grabauskas and R. M. Bradley Frequency-Dependent Properties of Inhibitory Synapses in the Rostral Nucleus of the Solitary Tract J Neurophysiol, January 1, 2003; 89(1): 199 - 211. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Galarreta and S. Hestrin Electrical and chemical synapses among parvalbumin fast-spiking GABAergic interneurons in adult mouse neocortex PNAS, September 17, 2002; 99(19): 12438 - 12443. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
V. Lopantsev and P. A. Schwartzkroin GABAA-Dependent Chloride Influx Modulates Reversal Potential of GABAB-Mediated IPSPs in Hippocampal Pyramidal Cells J Neurophysiol, June 1, 2001; 85(6): 2381 - 2387. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. S. Fitzpatrick, G. Akopian, and J. P. Walsh Short-Term Plasticity at Inhibitory Synapses in Rat Striatum and Its Effects on Striatal Output J Neurophysiol, May 1, 2001; 85(5): 2088 - 2099. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. Anchisi, B. Scelfo, and F. Tempia Postsynaptic Currents in Deep Cerebellar Nuclei J Neurophysiol, January 1, 2001; 85(1): 323 - 331. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
V. Lopantsev and P. A. Schwartzkroin GABAA-Dependent Chloride Influx Modulates GABAB-Mediated IPSPs in Hippocampal Pyramidal Cells J Neurophysiol, September 1, 1999; 82(3): 1218 - 1223. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. Maric, I. Maric, X. Wen, J.-M. Fritschy, W. Sieghart, J. L. Barker, and R. Serafini GABAA Receptor Subunit Composition and Functional Properties of Cl- Channels with Differential Sensitivity to Zolpidem in Embryonic Rat Hippocampal Cells J. Neurosci., June 15, 1999; 19(12): 4921 - 4937. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. I. Banks, T.-B. Li, and R. A. Pearce The Synaptic Basis of GABAA,slow J. Neurosci., February 15, 1998; 18(4): 1305 - 1317. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. Wu and L. S. Leung Partial Hippocampal Kindling Decreases Efficacy of Presynaptic GABAB Autoreceptors in CA1 J. Neurosci., December 1, 1997; 17(23): 9261 - 9269. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
N. Hajos and I. Mody Synaptic Communication among Hippocampal Interneurons: Properties of Spontaneous IPSCs in Morphologically Identified Cells J. Neurosci., November 1, 1997; 17(21): 8427 - 8442. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. Pare, E. Lebel, and E. J. Lang Differential Impact of Miniature Synaptic Potentials on the Soma and Dendrites of Pyramidal Neurons In Vivo J Neurophysiol, September 1, 1997; 78(3): 1735 - 1739. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
W. Morishita, S. A. Kirov, T. A. Pitler, L. A. Martin, R. A. Lenz, and B. E. Alger N-Ethylmaleimide Blocks Depolarization-Induced Suppression of Inhibition and Enhances GABA Release in the Rat Hippocampal Slice In Vitro J. Neurosci., February 1, 1997; 17(3): 941 - 950. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. Sah and J. M. Bekkers Apical Dendritic Location of Slow Afterhyperpolarization Current in Hippocampal Pyramidal Neurons: Implications for the Integration of Long-Term Potentiation J. Neurosci., August 1, 1996; 16(15): 4537 - 4542. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. M. Craig, G. Banker, W. Chang, M. E. McGrath, and A. S. Serpinskaya Clustering of Gephyrin at GABAergic but Not Glutamatergic Synapses in Cultured Rat Hippocampal Neurons J. Neurosci., May 15, 1996; 16(10): 3166 - 3177. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
