Linked Life Data

8201424

Source:http://linkedlifedata.com/resource/pubmed/id/8201424

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1994-7-6
pubmed:abstractText
1. Single-channel properties of voltage-dependent calcium channels were investigated in rat melanotropes in short-term primary culture. Unitary currents were resolved using the cell-attached configuration. 2. Depolarizations higher than -50 mV activated a population of 8.1-pS calcium channels [low-voltage activated (LVA)]. The LVA channel ensembles displayed a monoexponential time course of inactivation and a sigmoidal time course of activation fitted best by an m2h Hodgkin-Huxley-type model. Microscopic kinetic analysis suggested that at least one open state, two closed states, and one inactivated state are involved in channel gating. 3. At potentials positive to -20 mV a second class of calcium channels was activated with a conductance of 24.7 pS [high-voltage activated (HVA)]. HVA channels display different gating modes. Gating with high open probability (mode 2) and low open probability (mode 1) as well as blank traces (mode 0) are observed. The HVA channels were heterogeneous with respect to their inactivation properties. Ensembles that decayed entirely during a 300-ms test pulse as well as nondecaying ensembles were observed. Both HVA channel subtypes displayed sigmoidal activation, which was fitted by an m2 model. Microscopic kinetic analysis suggested that at least one open state and two closed states are involved in mode two gating of both HVA channel subtypes. 4. Depolarizing prepulses did not recruit or facilitate calcium channel activity in response to a test pulse, but inactivating HVA channel activity was strongly reduced. Depolarizing prepulses (+50 mV) did not affect the probability of opening of the noninactivating HVA channel. 5. The voltage dependence and kinetics of the LVA as well as both HVA channels are in good agreement with previously published data on the properties of the various calcium current components derived from whole-cell recordings of rat melanotropes. The data suggest that a T-type as well as two L-type channels (an inactivating and noninactivating channel) underlie the calcium current in these cells.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Mar
pubmed:issn
0022-3077
pubmed:author
pubmed:issnType
Print
pubmed:volume
71
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
840-55
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1994
pubmed:articleTitle
Single-channel properties of high- and low-voltage-activated calcium channels in rat pituitary melanotropic cells.
pubmed:affiliation
Department of Neurophysiology, Faculty of Biology, Medical Faculty, Vrije Universiteit, Amsterdam, The Netherlands.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't