Linked Life Data

1403085

Source:http://linkedlifedata.com/resource/pubmed/id/1403085

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
10
pubmed:dateCreated
1992-11-18
pubmed:abstractText
The inhibitory GABAergic projection of thalamic nucleus reticularis (nRt) neurons onto thalamocortical relay cells (TCs) is important in generating the normal thalamocortical rhythmicity of slow wave sleep, and may be a key element in the production of abnormal rhythms associated with absence epilepsy. Both TCs and nRt cells can generate prominent Ca(2+)-dependent low-threshold spikes, which evoke bursts of Na(+)-dependent fast spikes, and are influential in rhythm generation. Substantial differences in the pattern of burst firing in TCs versus nRt neurons led us to hypothesize that there are distinct forms of transient Ca2+ current (I(T)) underlying burst discharges in these two cell types. Using whole-cell voltage-clamp recordings, we analyzed I(T) in acutely isolated TCs and nRt neurons and found three key differences in biophysical properties. (1) The transient Ca2+ current in nRt neurons inactivated much more slowly than I(T) in TCs. This slow current is thus termed I(Ts). (2) The rate of inactivation for I(Ts) was nearly voltage independent. (3) Whole-cell I(Ts) amplitude was increased when Ba2+ was substituted for Ca2+ as the charge carrier. In addition, activation kinetics were slower for I(Ts) and the activation range was depolarized compared to that for I(T). Other properties of I(Ts) and I(T) were similar, including steady-state inactivation and sensitivities to blockade by divalent cations, amiloride, and antiepileptic drugs. Our findings demonstrate that subtypes of transient Ca2+ current are present in two different classes of thalamic neurons. The properties of I(Ts) lead to generation of long-duration calcium-dependent spike bursts in nRt cells. The resultant prolonged periods of GABA release onto TCs would play a critical role in maintaining rhythmicity by inducing TC hyperpolarization and promoting generation of low-threshold calcium spikes within relay nuclei.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Oct
pubmed:issn
0270-6474
pubmed:author
pubmed:issnType
Print
pubmed:volume
12
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
3804-17
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1992
pubmed:articleTitle
A novel T-type current underlies prolonged Ca(2+)-dependent burst firing in GABAergic neurons of rat thalamic reticular nucleus.
pubmed:affiliation
Department of Neurology and Neurological Sciences, Stanford University Medical Center, California 94305.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't