Linked Life Data

8967455

Source:http://linkedlifedata.com/resource/pubmed/id/8967455

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
5 Pt 1
pubmed:dateCreated
1996-12-6
pubmed:abstractText
RT4-B is one of several cell lines derived from a multipotent stem cell line, RT4-AC, which originated from a rat peripheral neurotumor. Based on Northern blot and ribonuclease protection experiments, RT4-B8 cells have been proposed to express rat cardiac Na channel mRNA as the major isoform. We report here direct electrophysiological evidence that the expressed voltage-gated Na channels in the RT4-B8 cell line are of the cardiac phenotype with no evidence for subpopulations expressing other Na channel isoforms. Current activation half point (conductance) was -41 +/- 5 mV (n = 7) and the steady-state voltage-dependent availability half point was -89 +/- 1 mV. As expected for cardiac Na channels, the half concentration of block for tetrodotoxin block was 0.74 microM, for saxitoxin (STX) was 0.15 microM, and for the class 2B divalent cation Cd2+ was 67 microM. Block was well described by single-site dose-response relationships with no indication of a subpopulation with "neuronal" affinity. Single-channel conductance (140 mM Na+) was 10 pS and predicted the average number of channels open at peak Na current to be 3 channels/microns2. [3H]STX binding data were also consistent with a single population of low-affinity STX binding sites and predicted channel density to be 11 sites/microns2. No inwardly or outwardly rectifying K or Ca currents were detected electrophysiologically, although in some cells a small time-independent Cl current was detected. Reverse transcription-polymerase chain reaction of mRNA isolated from RT4-B8 cells demonstrated the presence of rat cardiac (rH1) and brain IIa alpha-subunit mRNA, as well as mRNA for the Na channel beta 1-subunit. Northern blot analysis confirmed the predominance of the rat cardiac Na mRNA compared with brain IIa. The beta 1-subunit mRNA levels were significantly lower than those detected in rat brain and heart mRNA but were comparable to the low level of beta 1-subunit mRNA detected in isolated rat ventricular myocytes.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
May
pubmed:issn
0002-9513
pubmed:author
pubmed:issnType
Print
pubmed:volume
270
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
C1522-31
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1996
pubmed:articleTitle
Cardiac sodium channels expressed in a peripheral neurotumor-derived cell line, RT4-B8.
pubmed:affiliation
Department of Medicine, University of Chicago, Illinois 60637, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't