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Predicate | Object |
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rdf:type | |
lifeskim:mentions | |
pubmed:issue |
6
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pubmed:dateCreated |
1992-3-5
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pubmed:abstractText |
The electrophysiologic mode of action and potency of the verapamil derivative YS 035 (N,N-bis-(3,4-dimethoxyphenethyl)-N-methyl amine) were investigated in sheep cardiac Purkinje fibres. Action potential duration measured at a repolarization level of -60 mV (APD-60) and membrane currents recorded with the two-microelectrode voltage-clamp technique were evaluated. At 10 mumols/l YS 035 APD-60 was increased to about 115% of reference. Prolongation measured as percentage of the respective control exhibited on the average no dependence on stimulation frequency (0.17-2 Hz). At 100 mumols/l membrane became depolarized to about -50 mV and action potentials could no longer be elicited. Further study was focussed on effects on outward currents, mostly activated at a frequency of 0.05 Hz. Transient outward current (ito) was completely blocked at 100 mumols/l and half-maximal inhibition occurred at about 14 mumols/l. Inwardly rectifying potassium current (ik1) was reduced to 47% of reference at 100 mumols/l. An initially activating outward current at positive membrane potentials (iinst) was reduced to 73% at 100 mumols/l. Time-dependent (delayed) outward current (iK) was on the average not affected up to 100 mumols/l. Besides inhibition of repolarizing outward currents YS 035 completely blocked pacemaker current (if) at 100 mumols/l and half-maximal reduction was achieved at 5 mumols/l. YS 035 (1-100 mumols/l) did not clearly affect time constants of activation at selected test potentials (IK: +35 mV; if: -90 mV) or inactivation (ito: 0 mV). Voltage-dependent control mechanisms of currents (ito, if) were not influenced by YS 035 but the amount of available current was reduced.(ABSTRACT TRUNCATED AT 250 WORDS)
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pubmed:language |
eng
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pubmed:journal | |
pubmed:citationSubset |
IM
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pubmed:chemical | |
pubmed:status |
MEDLINE
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pubmed:month |
Dec
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pubmed:issn |
0028-1298
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pubmed:author | |
pubmed:issnType |
Print
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pubmed:volume |
344
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
653-61
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pubmed:dateRevised |
2006-11-15
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pubmed:meshHeading |
pubmed-meshheading:1775198-Action Potentials,
pubmed-meshheading:1775198-Animals,
pubmed-meshheading:1775198-Calcium Channel Blockers,
pubmed-meshheading:1775198-Electric Stimulation,
pubmed-meshheading:1775198-Heart,
pubmed-meshheading:1775198-Membrane Potentials,
pubmed-meshheading:1775198-Phenethylamines,
pubmed-meshheading:1775198-Purkinje Fibers,
pubmed-meshheading:1775198-Sheep
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pubmed:year |
1991
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pubmed:articleTitle |
Inhibition of potassium outward currents and pacemaker current in sheep cardiac Purkinje fibres by the verapamil derivative YS 035.
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pubmed:affiliation |
Institut für Pharmakologie, Universität Düsseldorf, Federal Republic of Germany.
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pubmed:publicationType |
Journal Article,
Research Support, Non-U.S. Gov't
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