| Effects of potassium conductance inhibitors on spontaneous diastolic depolarization and abnormal automaticity in human atrial fibers. | |
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MedLine Citation:
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PMID: 3019294 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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The capability of generating spontaneous diastolic depolarization and automaticity was investigated in vitro by means of standard microelectrode techniques in 50 human atrial preparations. Samples were classified within two groups: group 1 was composed of 12 well-polarized preparations exhibiting action potentials that were fast responses (mean maximum diastolic potential: -75.5 mV and Vmax greater than 100 V/s); group 2 was composed of 38 partially-depolarized samples (mean maximum diastolic potential: -50.3 mV and Vmax less than 10 V/s) and was further divided into two subgroups. Subgroup 2A consisted of 20 spontaneously beating preparations and subgroup 2B consisted of 18 non-automatic partially-depolarized specimens. Highly-polarized fibers from group 1, although exhibiting a slight diastolic depolarization which was almost entirely suppressed by 2 mM caesium, never presented spontaneous activity under our experimental conditions. 90% of automatic fibers from subgroup 2A were sampled from dilated atria. In automatic preparations, diastolic depolarization was usually separated into two phases: an initial phase, also present in non-automatic fibers, and a late phase. Changes in the initial phase were not accompanied by concomitant changes in the spontaneous rate. Abnormal automaticity was clearly related to the late diastolic phase (absent in non-automatic fibers), the generation of which appeared to be a specific property of automatic fibers. The use of K conductance inhibitors (caesium, 4-aminopyridine, barium, low K solutions) provided indirect evidence that neither delayed outward ix current nor if type inward current are principally responsible for abnormal automaticity. |
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Authors:
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D Escande; E Coraboeuf; C Planché; F Lacour-Gayet |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Basic research in cardiology Volume: 81 ISSN: 0300-8428 ISO Abbreviation: Basic Res. Cardiol. Publication Date: 1986 May-Jun |
Date Detail:
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Created Date: 1986-10-23 Completed Date: 1986-10-23 Revised Date: 2007-11-15 |
Medline Journal Info:
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Nlm Unique ID: 0360342 Medline TA: Basic Res Cardiol Country: GERMANY, WEST |
Other Details:
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Languages: eng Pagination: 244-57 Citation Subset: IM |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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4-Aminopyridine Aminopyridines / pharmacology Arrhythmias, Cardiac / chemically induced* Cesium / pharmacology Diastole / drug effects* Electric Conductivity Electrophysiology Heart / drug effects* Heart Atria Humans Myocardial Contraction / drug effects* Potassium / antagonists & inhibitors*, physiology |
| Chemical | |
Reg. No./Substance:
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0/Aminopyridines; 504-24-5/4-Aminopyridine; 7440-09-7/Potassium; 7440-46-2/Cesium |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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