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Electrical properties and response to noradrenaline of individual heart cells isolated from human ventricular tissue

Electrical properties and response to noradrenaline of individual heart cells isolated from human... SUMMARY The analysis of the electrical properties and response to catecholamines of cardiac tissue is greatly simplified by the use of single cell preparations. In this study individual cells isolated from human ventricular tissue were used to estimate cellular sarcolemmal resistance and capacitance and to record the time course of the response to ionophoretically applied noradrenaline. The mean input capacitance of the cells is consistent with a surface membrane area of approximately 15000 μm2 if the specific membrane capacitance is 1 μF·cm−2. This is larger than might be expected from the measured external dimensions of the cell and is compatible with the presence of surface membrane infoldings and caveolae. At membrane potentials close to −75 mV the mean cell input resistance was approximately 40 MΩ, giving a specific membrane resistance of 6 kΩ·cm2 if mean membrane area is 15000 μm2 and consistent with the assumption that the isolated cells have sealed intercalated discs under the experimental conditions used. Ionophoretically applied noradrenaline produced a pronounced prolongation of the plateau phase of the action potential, but this effect developed over many seconds. The slow onset of action is not compatible with the kinetics of free extracellular diffusion of catecholamine but may reflect molecular events that occur between noradrenaline binding to membrane receptors and the final cellular response. Under voltage-clamp conditions, the cells showed a time dependent inward current consistent with the rapid activation and decay of a sarcolemmal calcium conductance. human ventricle, isolated cardiac myocytes, electrical properties, noradrenaline, voltage clamp, calcium current This content is only available as a PDF. Author notes * Present address: Department of Physiology, Marischal College, University of Aberdeen, Aberdeen † University Laboratory of Physiology, University of Oxford, Oxford. ‡ Department of Pharmacology, University of Oxford, Oxford. Copyright © 1986, European Society of Cardiology http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Cardiovascular Research Oxford University Press

Electrical properties and response to noradrenaline of individual heart cells isolated from human ventricular tissue

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Publisher
Oxford University Press
Copyright
Copyright © 1986, European Society of Cardiology
ISSN
0008-6363
eISSN
1755-3245
DOI
10.1093/cvr/20.12.869
Publisher site
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Abstract

SUMMARY The analysis of the electrical properties and response to catecholamines of cardiac tissue is greatly simplified by the use of single cell preparations. In this study individual cells isolated from human ventricular tissue were used to estimate cellular sarcolemmal resistance and capacitance and to record the time course of the response to ionophoretically applied noradrenaline. The mean input capacitance of the cells is consistent with a surface membrane area of approximately 15000 μm2 if the specific membrane capacitance is 1 μF·cm−2. This is larger than might be expected from the measured external dimensions of the cell and is compatible with the presence of surface membrane infoldings and caveolae. At membrane potentials close to −75 mV the mean cell input resistance was approximately 40 MΩ, giving a specific membrane resistance of 6 kΩ·cm2 if mean membrane area is 15000 μm2 and consistent with the assumption that the isolated cells have sealed intercalated discs under the experimental conditions used. Ionophoretically applied noradrenaline produced a pronounced prolongation of the plateau phase of the action potential, but this effect developed over many seconds. The slow onset of action is not compatible with the kinetics of free extracellular diffusion of catecholamine but may reflect molecular events that occur between noradrenaline binding to membrane receptors and the final cellular response. Under voltage-clamp conditions, the cells showed a time dependent inward current consistent with the rapid activation and decay of a sarcolemmal calcium conductance. human ventricle, isolated cardiac myocytes, electrical properties, noradrenaline, voltage clamp, calcium current This content is only available as a PDF. Author notes * Present address: Department of Physiology, Marischal College, University of Aberdeen, Aberdeen † University Laboratory of Physiology, University of Oxford, Oxford. ‡ Department of Pharmacology, University of Oxford, Oxford. Copyright © 1986, European Society of Cardiology

Journal

Cardiovascular Research – Oxford University Press

Published: Dec 1, 1986

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