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rdf:type |
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lifeskim:mentions |
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pubmed:dateCreated |
1996-11-7
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pubmed:abstractText |
1. Spike adaptation of neocortical pyramidal neurones was studied with sharp electrode recordings in slices of guinea-pig parietal cortex and whole-cell patch recordings of mouse somatosensory cortex. Repetitive intracellular stimulation with 1 s depolarizing pulses delivered at intervals of < 5 s caused slow, cumulative adaptation of spike firing, which was not associated with a change in resting conductance, and which persisted when Co2+ replaced Ca2+ in the bathing medium. 2. Development of slow cumulative adaptation was associated with a gradual decrease in maximal rates of rise of action potentials, a slowing in the post-spike depolarization towards threshold, and a positive shift in the threshold voltage for the next spike in the train; maximal spike repolarization rates and after-hyperpolarizations were unchanged. 3. The data suggested that slow adaptation reflects use-dependent removal of Na+ channels from the available pool by an inactivation process which is much slower than fast, Hodgkin-Huxley-type inactivation. 4. We therefore studied the properties of Na+ channels in layer II-III mouse neocortical cells using the cell-attached configuration of the patch-in-slice technique. These had a slope conductance of 18 +/- 1 pS and an extrapolated reversal potential of 127 +/- 6 mV above resting potential (Vr) (mean +/- S.E.M.; n = 5). Vr was estimated at -72 +/- 3 mV (n = 8), based on the voltage dependence of the steady-state inactivation (h infinity) curve. 5. Slow inactivation (SI) of Na+ channels had a mono-exponential onset with tau on between 0.86 and 2.33 s (n = 3). Steady-state SI was half-maximal at -43.8 mV and had a slope of 14.4 mV (e-fold)-1. Recovery from a 2 s conditioning pulse was bi-exponential and voltage dependent; the slow time constant ranged between 0.45 and 2.5 s at voltages between-128 and -68 mV. 6. The experimentally determined parameters of SI were adequate to simulate slow cumulative adaptation of spike firing in a single-compartment computer model. 7. Persistent Na+ current, which was recorded in whole-cell configuration during slow voltage ramps (35 mV s-1), also underwent pronounced SI, which was apparent when the ramp was preceded by a prolonged depolarizing pulse.
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pubmed:commentsCorrections |
http://linkedlifedata.com/resource/pubmed/commentcorrection/8735696,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8735696-12991237,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8735696-1316183,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8735696-1336556,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8735696-1645413,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8735696-1656476,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8735696-1691879,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8735696-2411848,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8735696-2441037,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8735696-2452862,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8735696-2453799,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8735696-2454285,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8735696-2538843,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8735696-2579215,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8735696-2607782,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8735696-2714879,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8735696-2845252,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8735696-3351569,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8735696-5410485,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8735696-5675050,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8735696-6279236,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8735696-6296328,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8735696-6308224,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8735696-6434729,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8735696-722569,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8735696-7265003,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8735696-7473260,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8735696-7507618,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8735696-7528275,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8735696-7716524,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8735696-7904302,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8735696-7931536,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8735696-8107777,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8735696-8201401,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8735696-8229187,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8735696-8381170,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8735696-8381857,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8735696-8439739,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8735696-8592214,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8735696-8845165
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pubmed:language |
eng
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pubmed:journal |
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pubmed:citationSubset |
IM
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pubmed:chemical |
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pubmed:status |
MEDLINE
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pubmed:month |
May
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pubmed:issn |
0022-3751
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pubmed:author |
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pubmed:issnType |
Print
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pubmed:day |
15
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pubmed:volume |
493 ( Pt 1)
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
83-97
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pubmed:dateRevised |
2010-9-10
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pubmed:meshHeading |
pubmed-meshheading:8735696-Action Potentials,
pubmed-meshheading:8735696-Animals,
pubmed-meshheading:8735696-Computer Simulation,
pubmed-meshheading:8735696-Female,
pubmed-meshheading:8735696-Guinea Pigs,
pubmed-meshheading:8735696-Kinetics,
pubmed-meshheading:8735696-Male,
pubmed-meshheading:8735696-Mice,
pubmed-meshheading:8735696-Microelectrodes,
pubmed-meshheading:8735696-Patch-Clamp Techniques,
pubmed-meshheading:8735696-Pyramidal Cells,
pubmed-meshheading:8735696-Sodium,
pubmed-meshheading:8735696-Sodium Channel Blockers
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pubmed:year |
1996
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pubmed:articleTitle |
Slow inactivation of Na+ current and slow cumulative spike adaptation in mouse and guinea-pig neocortical neurones in slices.
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pubmed:affiliation |
Department of Physiology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beersheva, Israel.
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pubmed:publicationType |
Journal Article,
In Vitro,
Research Support, U.S. Gov't, Non-P.H.S.,
Research Support, Non-U.S. Gov't
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