Linked Life Data

2890419

Source:http://linkedlifedata.com/resource/pubmed/id/2890419

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1988-1-20
pubmed:abstractText
D890, a derivative of the Ca2+ channel antagonist D600, was intracellularly applied from conventional microelectrodes into pyramidal neurons of neocortical slices. The effects of D890 were ascertained by evaluating alterations in membrane properties following drug administration and by comparing these neurons to untreated controls. The amplitude of action potentials (APs) evoked by depolarizing current pulses was attenuated by up to 30% within about 15 min after impalement with D890-containing electrodes. AP rate of rise was reduced by up to 80% and duration was increased. These effects were dependent upon the rate of stimulation. When depolarizing pulses were delivered at low rates of stimulation (e.g. 0.1 Hz), the overshoot of evoked APs declined by about 10%. At higher frequencies (greater than 2 Hz) the AP overshoot decreased by up to 90%. These effects were mostly reversible on decreasing the frequency of stimulation. A half maximal effect was attained at about 1 Hz, when APs of control neurons were unaltered. In neurons impaled with D890-containing electrodes, depolarizing current pulses delivered in the presence of tetraethylammonium (TEA) and tetrodotoxin elicited high threshold calcium spikes which had a duration between 20 and 200 ms. In the early phase of D890 application, the duration of Ca2+ spikes decreased in a reversible frequency-dependent manner; after prolonged application, however, the recovery was incomplete. On the average, Ca2+ spike amplitude and duration decreased by 20% and 50%, respectively, suggesting that D890 usually produces an incomplete blockade of the underlying CA current. The duration of the slow envelope of orthodromically evoked epileptiform paroxysmal depolarizing shifts (DSs), induced by bath application of 10(-5) M bicuculline, was frequency dependent and consistently increased from about 20 ms to 150 ms (half amplitude width) at frequencies above 0.5 Hz. In the presence of D890, the action potentials superimposed on the slow envelope of the DS were attenuated, but neither the amplitude nor the frequency-dependent progressive prolongation of the DS was altered. Application of TEA in the presence of bicuculline (10(-5) M) increased the amplitude and duration of the DS in neurons impaled with D890-containing electrodes. Under these conditions, the durations of DSs evoked by low frequency orthodromic stimulation (greater than 0.5 Hz) were still progressively prolonged, while, in the same neuron, directly evoked Ca2+ spikes progressively decreased in amplitude and duration.(ABSTRACT TRUNCATED AT 400 WORDS)
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
0006-8993
pubmed:author
pubmed:issnType
Print
pubmed:day
29
pubmed:volume
422
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
63-73
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1987
pubmed:articleTitle
Effect of D890 on membrane properties of neocortical neurons.
pubmed:affiliation
Department of Neurology, Stanford University School of Medicine, CA 94305.
pubmed:publicationType
Journal Article, In Vitro, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't