Linked Life Data

9435183

Source:http://linkedlifedata.com/resource/pubmed/id/9435183

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1998-2-11
pubmed:abstractText
We examined the effect of the anticonvulsant phenytoin (PT) (20-200 microM) on the persistent Na+ current (INaP), INaP-dependent membrane potential responses and repetitive firing in layer 5 pyramidal neurons in a slice preparation of rat sensorimotor cortex. INaP measured directly with voltage-clamp was reduced in a concentration-dependent manner with an apparent EC50 value of 78 microM. Clear effects on current-evoked membrane potential responses were apparent at 50 microM PT: Subthreshold, depolarizing membrane potential rectification was reduced, rheobase current was increased and the relation between firing rate and injected current was shifted to the right, but action potential amplitude and duration were unaffected. We ascribed these effects of PT largely to the reduction of INaP. A slow decline of firing rate during the injected current pulse also became apparent at moderate PT concentrations. When PT concentration was raised to 150 to 200 microM, this slow adaption was enhanced markedly, and firing ceased during a sufficiently large current pulse. This enhanced slow adaptation and the cessation of firing were associated with a marked decline of spike amplitude and a rise in spike firing level during successive interspike intervals. We ascribe these effects largely to the action of PT on the transient Na+ current. We conclude that the reduction in cortical neuronal excitability by PT depends partly on its reduction of INaP, the effects of INaP blockade are apparent at PT concentrations lower than those required to abolish tonic firing and the cells need not be excessively depolarized for PT to decrease excitability by its effect on INaP.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
0022-3565
pubmed:author
pubmed:issnType
Print
pubmed:volume
284
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
228-37
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1998
pubmed:articleTitle
Reduction of cortical pyramidal neuron excitability by the action of phenytoin on persistent Na+ current.
pubmed:affiliation
Department of Physiology and Biophysics, University of Washington School of Medicine, Seattle 98195-7290, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't