Nonlinear changes of transmembrane potential caused by defibrillation shocks in strands of cultured myocytes

Departments of 1  Biomedical Engineering, 2  Medicine, and 3  Physiology, University of Alabama at Birmingham, Birmingham, Alabama 35294; and 4  Department of Physiology, University of Bern, 3012 Bern, Switzerland Organization of cardiac tissue into cell strands and layers has been implicated in cha...

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Bibliographic Details
Published in:American journal of physiology. Heart and circulatory physiology 2000-03, Vol.278 (3), p.H688-H697
Main Authors: Fast, Vladimir G, Rohr, Stephan, Ideker, Raymond E
Format: Article
Language:English
Subjects:
Animals
Animals, Newborn
Barium Compounds - pharmacology
Cell Size
Cells, Cultured
Chlorides - pharmacology
Electric Countershock
Electrodes
Electroshock
Heart - physiology
Membrane Potentials
Potassium Channel Blockers
Potassium Channels - physiology
Rats
Rats, Wistar
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Summary:Departments of 1  Biomedical Engineering, 2  Medicine, and 3  Physiology, University of Alabama at Birmingham, Birmingham, Alabama 35294; and 4  Department of Physiology, University of Bern, 3012 Bern, Switzerland Organization of cardiac tissue into cell strands and layers has been implicated in changes of transmembrane potential ( V m ) during defibrillation. To determine the shock-induced V m in such structures, cell strands of variable width [strand width (SW)   = 0.15-2 mm] were grown in culture. Uniform-field shocks with variable strength [shock strength (SS) = 2-50 V/cm] were applied across strands during the action potential (AP) plateau, and V m were measured optically. Three different types of V m were observed. Small V m [200%APA), a second time-dependent shift of V m to more positive levels was observed in the hyperpolarized portions of strands, causing reduction of the V m asymmetry. We conclude that during application of shocks to cell strands during the AP plateau, passive changes of V m were followed by two voltage- and time-dependent shifts of V m , possibly reflecting changes of ionic currents or membrane electroporation. stimulation; optical mapping; voltage-sensitive dyes; cell cultures
ISSN:0363-6135
1522-1539
DOI:10.1152/ajpheart.2000.278.3.h688