Linked Life Data

8389832

Source:http://linkedlifedata.com/resource/pubmed/id/8389832

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
5
pubmed:dateCreated
1993-7-15
pubmed:abstractText
1. Ca2+ currents were investigated in neurons acutely isolated from adult human temporal neocortex. The aim was to compare the basic characteristics of the currents with those previously described in animals and to examine the effects of dihydropyridine Ca2+ antagonists and antiepileptic drugs. The tissue, obtained from patients undergoing temporal lobe surgery for medically intractable epilepsy, was sliced, incubated in papain, and triturated. 2. Most of the isolated neurons (34 of 36) were judged to be pyramidal cells by their morphology. Whole-cell voltage-clamp recordings revealed two components of Ca2+ current: 1) a low-threshold (T-type) current that was transient, small in amplitude, and required hyperpolarization more negative than -70 mV for removal of inactivation and 2) a high-threshold current that was slowly inactivating and was available for activation from more positive potentials. The characteristics of the Ca2+ currents were very similar to those in the neocortical neurons of young rats, although the low-threshold current was less prominent in the human cells. 3. Subcomponents of the high-threshold current were identified by pharmacology. About 20% of the peak current was blocked by omega-conotoxin GVIA (presumed N current) and 40-50% of the peak current was blocked by micromolar concentrations of the dihydropyridine Ca2+ antagonists nifedipine and nimodipine (presumed L current). In two neurons tested with a range of nimodipine concentrations, the threshold for suppression of the high-threshold current was approximately 10 nM. 4. The antiepileptic agents ethosuximide, carbamazepine, and valproate did not affect the Ca2+ currents at therapeutically relevant concentrations. Phenytoin marginally reduced the low- and high-threshold Ca2+ currents at 8 microM (a concentration corresponding to the upper therapeutic range). The results do not support the hypothesis that inhibition of Ca2+ currents in neocortical pyramidal neurons is a major action of these drugs.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
May
pubmed:issn
0022-3077
pubmed:author
pubmed:issnType
Print
pubmed:volume
69
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1596-606
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1993
pubmed:articleTitle
Calcium currents in acutely isolated human neocortical neurons.
pubmed:affiliation
Department of Physiology and Biophysics, University of Washington, Seattle 98195.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't