Document Detail

Contribution of I Kr and I K1 to ventricular repolarization in canine and human myocytes: is there any influence of action potential duration?
MedLine Citation:
PMID:  18604626     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: The aim of the present work was to study the profile of the rapid delayed rectifier potassium current (I (Kr)) and the inward rectifier potassium current (I (K1)) during ventricular repolarization as a function of action potential duration and rate of repolarization. METHODS: Whole cell configuration of the patch clamp technique was used to monitor I (Kr) and I (K1) during the action potential plateau and terminal repolarization. Action potentials recorded at various cycle lengths (0.4-5 s) and repolarizing voltage ramps having various slopes (0.5-3 V/s) were used as command signals. I (Kr) and I (K1) were identified as difference currents dissected by E-4031 and BaCl(2), respectively. RESULTS: Neither peak amplitudes nor mean values of I (Kr) and I (K1) recorded during the plateau of canine action potentials were influenced by action potential duration. The membrane potential where I (Kr) and I (K1) peaked during the terminal repolarization was also independent of action potential duration. Similar results were obtained in undiseased human ventricular myocytes, and also in canine cells when I (Kr) and I (K1) were evoked using repolarizing voltage ramps of various slopes. Action potential voltage clamp experiments revealed that the peak values of I (Kr), I (K1), and net outward current during the terminal repolarization were independent of the pacing cycle length within the range of 0.4 and 5 s. CONCLUSIONS: The results indicate that action potential configuration fails to influence the amplitude of I (Kr) and I (K1) during the ventricular action potential in dogs and humans, suggesting that rate-dependent changes in action potential duration are not likely related to rate-dependent alterations in I (Kr) or I (K1) kinetics in these species.
Norbert Jost; Károly Acsai; Balázs Horváth; Tamás Bányász; István Baczkó; Miklós Bitay; Gábor Bogáts; Péter P Nánási
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2008-07-05
Journal Detail:
Title:  Basic research in cardiology     Volume:  104     ISSN:  1435-1803     ISO Abbreviation:  Basic Res. Cardiol.     Publication Date:  2009 Jan 
Date Detail:
Created Date:  2008-12-22     Completed Date:  2009-02-13     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0360342     Medline TA:  Basic Res Cardiol     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  33-41     Citation Subset:  IM    
Department of Pharmacology and Pharmacotherapy, University of Szeged, Szeged, Hungary.
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MeSH Terms
Action Potentials / physiology*
Barium Compounds / pharmacology
Chlorides / pharmacology
Electrophysiology / methods
KATP Channels / drug effects,  physiology*
Muscle Cells / physiology*
Patch-Clamp Techniques
Potassium Channels, Inwardly Rectifying / drug effects,  physiology*
Reference Values
Ventricular Function / physiology*
Reg. No./Substance:
0/Barium Compounds; 0/Chlorides; 0/KATP Channels; 0/Potassium Channels, Inwardly Rectifying; 10361-37-2/barium chloride

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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