Linked Life Data

21406973

Source:http://linkedlifedata.com/resource/pubmed/id/21406973

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
2011-7-1
pubmed:abstractText
Mouse and rat chromaffin cells (MCCs, RCCs) fire spontaneously at rest and their activity is mainly supported by the two L-type Ca(2+) channels expressed in these cells (Ca(v)1.2 and Ca(v)1.3). Using Ca(v)1.3(-/-) KO MCCs we have shown that Ca(v)1.3 possess all the prerequisites for carrying subthreshold currents that sustain low frequency cell firing near resting (0.5 to 2 Hz at -50 mV): low-threshold and steep voltage dependence of activation, slow and incomplete inactivation during pulses of several hundreds of milliseconds. Ca(v)1.2 contributes also to pacemaking MCCs and possibly even Na(+) channels may participate in the firing of a small percentage of cells. We now show that at potentials near resting (-50 mV), Ca(v)1.3 carries equal amounts of Ca(2+) current to Ca(v)1.2 but activates at 9 mV more negative potentials. MCCs express only TTX-sensitive Na(v)1 channels that activate at 24 mV more positive potentials than Ca(v)1.3 and are fully inactivating. Their blockade prevents the firing only in a small percentage of cells (13%). This suggests that the order of importance with regard to pacemaking MCCs is: Ca(v)1.3, Ca(v)1.2 and Na(v)1. The above conclusions, however, rely on the proper use of DHPs, whose blocking potency is strongly holding potential dependent. We also show that small increases of KCl concentration steadily depolarize the MCCs causing abnormally increased firing frequencies, lowered and broadened AP waveforms and an increased facility of switching "non-firing" into "firing" cells that may lead to erroneous conclusions about the role of Ca(v)1.3 and Ca(v)1.2 as pacemaker channels in MCCs.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:issn
1933-6969
pubmed:author
pubmed:issnType
Electronic
pubmed:volume
5
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
219-24
pubmed:meshHeading
pubmed:articleTitle
Are Ca(v)1.3 pacemaker channels in chromaffin cells? Possible bias from resting cell conditions and DHP blockers usage.
pubmed:affiliation
Department of Neuroscience, NIS Center, CNISM Research Unit, Torino, Italy.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't