Document Detail

Effects of low [K+]o on the electrical activity of human cardiac ventricular and Purkinje cells.
MedLine Citation:
PMID:  6871914     Owner:  NLM     Status:  MEDLINE    
Ventricular and Purkinje action potentials were recorded with a microelectrode in a strip of human papillary muscle. Lowering the K-content of the superfusing solution from 5.9 to 0.5 mmol.litre-1 at 37 degrees C hyperpolarised ventricular diastolic potential steadily as long as [K+]o was low (up to 70 min tested). Ventricular action potentials were transiently lengthened and then shortened. A positive inotropic effect was noted and attributed to Na-K pump inhibition since it was reversed by the addition of 2 mmol.litre-1 thallous chloride to the low [K+]o solution. Beyond 40 min, transient depolarisations and after-contractions were found. During the first minutes in low [K+]o, Purkinje diastolic potential was hyperpolarised and the action potential was lengthened at all levels of repolarisation. Afterwards, the Purkinje diastolic potential suddenly depolarised by 30 mV. Restoration of the control solution caused a slow repolarisation and then a sudden return of the diastolic potential to near control value. This was reproduced during drive (38 stim.min-1) and at rest. At the depolarised level of potential, stimulation elicited slow action potentials with diastolic slow depolarisation and spontaneous oscillations of potential appeared at rest. In Purkinje cells, increasing concentrations of tetrodotoxin from 10(-7) to 8 X 10(-6) mol.litre-1 in the control solution shifted the diastolic potential in negative direction by a few mV and shortened the action potential duration at all levels of repolarisation. The possible implications of these phenomena in the genesis of some cardiac arrhythmias is discussed.
G Christé
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Publication Detail:
Type:  In Vitro; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Cardiovascular research     Volume:  17     ISSN:  0008-6363     ISO Abbreviation:  Cardiovasc. Res.     Publication Date:  1983 Apr 
Date Detail:
Created Date:  1983-09-23     Completed Date:  1983-09-23     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  0077427     Medline TA:  Cardiovasc Res     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  243-50     Citation Subset:  IM    
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MeSH Terms
Action Potentials / drug effects
Diastole / drug effects
Heart / drug effects,  physiology*
Heart Ventricles / drug effects
Papillary Muscles / drug effects,  physiology
Potassium / pharmacology*
Purkinje Fibers / drug effects,  physiology
Tetrodotoxin / pharmacology
Ventricular Function
Reg. No./Substance:
4368-28-9/Tetrodotoxin; 7440-09-7/Potassium

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

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