Linked Life Data

8732495

Source:http://linkedlifedata.com/resource/pubmed/id/8732495

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
1996-11-12
pubmed:abstractText
The effects of cocaine on the duration of the cardiac action potential were investigated in isolated guinea-pig ventricular myocytes at 37 degrees C. Following a 10-min exposure of cells to 3 microM cocaine, APD90 increased significantly by +22 +/- 5% (n = 6). In contrast, following a ten minute exposure to 30 or 100 microM cocaine, APD90 was reduced by -24 +/- 6% (n = 5) and -53 +/- 2% (n = 8), respectively. The ionic basis for cocaine's effects on the APD was investigated using the whole cell voltage-clamp technique at 37 degrees C. Cocaine produced a concentration-dependent reduction in the amplitude of IK tail currents with an estimated IC50 of 4 microM. The kinetics and voltage dependence of the cocaine-sensitive current indicate that cocaine selectively blocks a current identical to the E-4031 sensitive current IKr. No significant reduction of the slow component of IK (IKs) was observed during exposure to 30 or 100 microM cocaine. High (30 and 100 microM) concentrations of cocaine also produced a significant reduction of both the L-type calcium current and the TTX-sensitive plateau current. Pre-treatment of cells with 10 microM TTX also converted the APD-shortening effect of 30 microM cocaine to one of APD-prolonging. This implies that cocaine block of a TTX-sensitive window current contributes to the APD-shortening effects produced by high concentrations of cocaine. We conclude that: (1) cocaine produces a biphasic concentration-dependent effect on repolarization in guinea-pig ventricular myocytes; and (2) this biphasic effect on repolarization results from differences in the sensitivity of inward and outward currents to the blocking effects of cocaine.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
0022-2828
pubmed:author
pubmed:issnType
Print
pubmed:volume
28
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
667-78
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed:year
1996
pubmed:articleTitle
Analysis of the ionic basis for cocaine's biphasic effect on action potential duration in guinea-pig ventricular myocytes.
pubmed:affiliation
Department of Pharmacology, Tulane University School of Medicine, New Orleans, LA 70112, USA.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, U.S. Gov't, P.H.S.