Abstract:
:We have used the rat hippocampal slice preparation as a model system for studying the epileptogenic consequences of a reduction in neuronal Na+-K+ pump activity. The cardiac glycosides (CGs) strophanthidin and dihydroouabain were used to inhibit the pump. These drugs had readily reversible effects, provided they were not applied for longer than 15-20 min. Hippocampal CA1 pyramidal cells were studied with intracellular recordings; population spike responses and changes in extracellular potassium concentration ([K+]o) were also measured in some experiments. This investigation focused on the possibility that intrinsic neuronal properties are affected by Na+-K+ pump inhibitors. The CGs altered the CA1 population response evoked by an orthodromic stimulus from a single spike to an epileptiform burst. Measurements of [K+]o showed that doses of CGs sufficient to cause bursting were associated with only minor (less than 1 mM) changes in resting [K+]o. However, the rate of K+ clearance from the extracellular space was moderately slowed, confirming that a decrease in pump activity had occurred. Intracellular recording indicated that CG application resulted in a small depolarization and apparent increase in resting input resistance of CA1 neurons. Although CGs caused a decrease in fast gamma-aminobutyric acid mediated inhibitory postsynaptic potentials (IPSPs), CGs could also enhance the latter part of the epileptiform burst induced by picrotoxin, an antagonist of these IPSPs. Since intrinsic Ca2+ conductances comprise a significant part of the burst, this suggested the possibility that Na+-K+ pump inhibitors affected an intrinsic neuronal conductance. CGs decreased the threshold for activation of Ca2+ spikes (recorded in TTX and TEA) without enhancing the spikes themselves, indicating that a voltage-dependent subthreshold conductance might be involved. The action of CGs on Ca2+ spike threshold could not be mimicked by increasing [K+]o up to 10 mM. A variety of K+ conductance antagonists, including TEA, 4-AP, Ba2+ (in zero Ca2+), and carbachol were ineffective in preventing the CG-induced threshold shift of the Ca2+ spike. The shift was also seen in the presence of a choline-substituted low Na+ saline. Enhancement of a slow inward Ca2+ current is a possible mechanism for the decrease in Ca2+ spike threshold; however, it is impossible to use the Ca2+ spike as an assay when testing the effects of blocking Ca2+ conductances. Therefore, we studied the influence of CGs on the membrane current-voltage (I-V) curve, since persistent voltage-dependent conductances appear as nonlinearities in the I-V plot obtained under current clamp.(ABSTRACT TRUNCATED AT 400 WORDS)
journal_name
J Neurophysioljournal_title
Journal of neurophysiologyauthors
McCarren M,Alger BEdoi
10.1152/jn.1987.57.2.496subject
Has Abstractpub_date
1987-02-01 00:00:00pages
496-509issue
2eissn
0022-3077issn
1522-1598journal_volume
57pub_type
杂志文章abstract::Synchronization between the firing times of simultaneously active motor units (MUs) is generally assumed to increase during fatiguing contractions. To date, however, estimates of MU synchronization have relied on indirect measures, derived from surface electromyographic (EMG) interference signals. This study used intr...
journal_title:Journal of neurophysiology
pub_type: 杂志文章
doi:10.1152/jn.00097.2016
更新日期:2016-06-01 00:00:00
abstract::Although previous research with human and nonhuman primates has examined the neural correlates of performance monitoring, discrepancies in methodology have limited our ability to make cross-species generalizations. One major obstacle arises from the use of different behavioral responses and tasks across different prim...
journal_title:Journal of neurophysiology
pub_type: 杂志文章
doi:10.1152/jn.00803.2011
更新日期:2012-05-01 00:00:00
abstract::1. Adaptation and disadaptation rates determine the temporal response properties of sensory receptor cells. In chemoreception, temporal filter properties of receptor cells are poorly understood. We studied the time course of disadaptation in lobster antennular chemoreceptor cells by using in situ high-resolution stimu...
journal_title:Journal of neurophysiology
pub_type: 杂志文章
doi:10.1152/jn.1996.76.2.1340
更新日期:1996-08-01 00:00:00
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journal_title:Journal of neurophysiology
pub_type: 杂志文章
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更新日期:2011-10-01 00:00:00
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journal_title:Journal of neurophysiology
pub_type: 杂志文章,评审
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更新日期:2017-04-01 00:00:00
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journal_title:Journal of neurophysiology
pub_type: 杂志文章
doi:10.1152/jn.1996.76.5.3382
更新日期:1996-11-01 00:00:00
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pub_type: 杂志文章
doi:10.1152/jn.1995.73.3.1135
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journal_title:Journal of neurophysiology
pub_type: 杂志文章
doi:10.1152/jn.1991.66.3.851
更新日期:1991-09-01 00:00:00
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journal_title:Journal of neurophysiology
pub_type: 杂志文章
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pub_type: 杂志文章
doi:10.1152/jn.1988.59.6.1657
更新日期:1988-06-01 00:00:00
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pub_type: 杂志文章
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更新日期:2012-09-01 00:00:00
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journal_title:Journal of neurophysiology
pub_type: 杂志文章
doi:10.1152/jn.1996.76.4.2474
更新日期:1996-10-01 00:00:00
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journal_title:Journal of neurophysiology
pub_type: 杂志文章
doi:10.1152/jn.00636.2009
更新日期:2009-11-01 00:00:00
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journal_title:Journal of neurophysiology
pub_type: 杂志文章
doi:10.1152/jn.00494.2014
更新日期:2014-12-01 00:00:00
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pub_type: 杂志文章,随机对照试验
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更新日期:2009-02-01 00:00:00
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journal_title:Journal of neurophysiology
pub_type: 杂志文章
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更新日期:2013-07-01 00:00:00
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journal_title:Journal of neurophysiology
pub_type: 杂志文章
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更新日期:2016-07-01 00:00:00
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journal_title:Journal of neurophysiology
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journal_title:Journal of neurophysiology
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pub_type: 杂志文章
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更新日期:1992-05-01 00:00:00
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journal_title:Journal of neurophysiology
pub_type: 杂志文章
doi:10.1152/jn.1987.57.5.1577
更新日期:1987-05-01 00:00:00
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journal_title:Journal of neurophysiology
pub_type: 杂志文章
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更新日期:1997-04-01 00:00:00
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journal_title:Journal of neurophysiology
pub_type: 杂志文章
doi:10.1152/jn.1997.77.5.2847
更新日期:1997-05-01 00:00:00
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journal_title:Journal of neurophysiology
pub_type: 杂志文章
doi:10.1152/jn.1994.71.1.229
更新日期:1994-01-01 00:00:00
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journal_title:Journal of neurophysiology
pub_type: 杂志文章
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更新日期:2016-06-01 00:00:00
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pub_type: 杂志文章
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更新日期:2007-02-01 00:00:00
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journal_title:Journal of neurophysiology
pub_type: 杂志文章
doi:10.1152/jn.1994.72.4.1530
更新日期:1994-10-01 00:00:00
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pub_type: 杂志文章
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更新日期:1995-10-01 00:00:00