Document Detail


Dose-dependent reduction of cardiac transmembrane potential by high-intensity electrical shocks.
MedLine Citation:
PMID:  9435619     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Cardiac tissue dysfunction can result from high-intensity electrical shocks and is manifested as changes in transmembrane potential (Vm). Ten-millisecond shock pulses (SPs) of varying intensity and polarity were applied to frog ventricle in diastole, and Vm was quantified directly under the stimulating electrode by an optical method using voltage-sensitive dye. As SP intensities were increased, the shock-induced action potential (AP) plateau and AP amplitude (APAs) decreased sigmoidally toward 75-85% of the control AP amplitude (APAc) and zero, respectively. APAs was shifted toward lower current densities for anodal compared with cathodal SPs (half-maximal values 185 and 238 mA/cm2, respectively; P = 0.02). Recovery of APAs was marginally significant 1 s after SP delivery (P = 0.063). The peak change in Vm during SP (across all intensity levels) was -200% APAc for anodal and +125% APAc for cathodal pulses. In conclusion, we show that SP reduces APA in a sigmoidal fashion at strengths > 10-20 x diastolic threshold and is more deleterious for anodal polarities.
Authors:
M Neunlist; L Tung
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Publication Detail:
Type:  In Vitro; Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The American journal of physiology     Volume:  273     ISSN:  0002-9513     ISO Abbreviation:  Am. J. Physiol.     Publication Date:  1997 Dec 
Date Detail:
Created Date:  1998-02-09     Completed Date:  1998-02-09     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0370511     Medline TA:  Am J Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  H2817-25     Citation Subset:  IM    
Affiliation:
Department of Physiology, School of Veterinary Medicine of Hannover, Germany.
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MeSH Terms
Descriptor/Qualifier:
Action Potentials / physiology*
Analysis of Variance
Animals
Diastole
Electroshock
Heart / physiology*
Heart Ventricles
Membrane Potentials
Rana pipiens
Systole
Time Factors
Grant Support
ID/Acronym/Agency:
HL-48266/HL/NHLBI NIH HHS

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


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