Document Detail

Comparison of the effects of regional ischemia and hyperkalemia on the membrane action potentials of the in situ pig heart. Experimental Cardiology Group, University of North Carolina at Chapel Hill.
MedLine Citation:
PMID:  9395164     Owner:  NLM     Status:  MEDLINE    
INTRODUCTION: This study was designed to determine the role of increased extracellular potassium [K+]e on action potential duration (APD) in the in situ porcine heart during acute regional no-flow ischemia. METHODS AND RESULTS: In open chest, anesthetized swine, an arterial shunt from the carotid artery to the mid-left anterior descending coronary artery was created through which a solution of KCl was infused to raise [K+]e. Myocardial [K+]e was determined by potassium-sensitive electrodes, and transmembrane action potential was recorded by floating glass microelectrode. During the first 2 minutes of ischemia, APD at 90% repolarization (APD90) lengthened by 31.2 +/- 1.1 msec (P < 0.05). The comparable increase in [K+]e alone shortened APD90. During the next 6 minutes of ischemia, [K+]e rose to 11.3 +/- 0.3 mM and APD90 showed a decrease. However, the comparable increase in [K+]e by infusion of KCl caused further shortening of APD90 at similar levels of [K+]e. CONCLUSIONS: Acutely ischemic myocardium showed a brief increase in APD90 during the first 2 minutes of ischemia, followed by a fall in APD90 after 2 minutes of ischemia, but the shortening is less than anticipated by the rise in [K+]e. Thus, we hypothesize that other component(s) of ischemia may inhibit action potential repolarization.
I Watanabe; A Kanda; C L Engle; L S Gettes
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Journal of cardiovascular electrophysiology     Volume:  8     ISSN:  1045-3873     ISO Abbreviation:  J. Cardiovasc. Electrophysiol.     Publication Date:  1997 Nov 
Date Detail:
Created Date:  1997-12-29     Completed Date:  1997-12-29     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  9010756     Medline TA:  J Cardiovasc Electrophysiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1229-36     Citation Subset:  IM    
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MeSH Terms
Action Potentials
Heart / physiopathology*
Hyperkalemia / physiopathology*
Myocardial Ischemia / physiopathology*
Grant Support
Comment In:
J Cardiovasc Electrophysiol. 1997 Nov;8(11):1237-8   [PMID:  9395165 ]

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