Linked Life Data

6088117

Source:http://linkedlifedata.com/resource/pubmed/id/6088117

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1984-10-25
pubmed:abstractText
We have investigated the mechanisms of blockade of calcium channel current by the dihydropyridines, e.g. nisoldipine, nitrendipine, and nicardipine. Membrane current was recorded in isolated calf Purkinje fibers using a two-microelectrode voltage-clamp technique, and voltage protocols were designed to identify voltage- and use-dependent block by these compounds systematically. Our results show that calcium channel blockade by dihydropyridine derivatives is strongly modulated by membrane potential. Block is more pronounced when current is measured from depolarized holding potentials, but in contrast to verapamil, this voltage-dependent block occurs in the absence of repetitive depolarizations. Use-dependent block by dihydropyridines is observed at pulse frequencies greater than 1 Hz. Our results suggest that dihydropyridines bind preferentially to the inactivated state of the calcium channel, and that the development of use-dependent block is related to the ionization constants of the compounds. Furthermore, binding is approximately one thousand times stronger to inactivated channels than to resting channels. This state-dependent difference in binding affinities may account for the previously reported contrast between electrophysiological and binding data for these compounds.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
0009-7330
pubmed:author
pubmed:issnType
Print
pubmed:volume
55
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
336-48
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1984
pubmed:articleTitle
Voltage-dependent block of calcium channel current in the calf cardiac Purkinje fiber by dihydropyridine calcium channel antagonists.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, U.S. Gov't, P.H.S.