Refractoriness in human atria: Time and voltage dependence of sodium channel availability
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Refractoriness in human atria: Time and voltage dependence of sodium channel availability. / Skibsbye, Lasse; Jespersen, Thomas; Christ, Torsten; Maleckar, Mary M; van den Brink, Jonas; Tavi, Pasi; Koivumäki, Jussi T.
in: J MOL CELL CARDIOL, Jahrgang 101, 20.10.2016, S. 26-34.Publikationen: SCORING: Beitrag in Fachzeitschrift/Zeitung › SCORING: Zeitschriftenaufsatz › Forschung › Begutachtung
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TY - JOUR
T1 - Refractoriness in human atria: Time and voltage dependence of sodium channel availability
AU - Skibsbye, Lasse
AU - Jespersen, Thomas
AU - Christ, Torsten
AU - Maleckar, Mary M
AU - van den Brink, Jonas
AU - Tavi, Pasi
AU - Koivumäki, Jussi T
N1 - Copyright © 2016 Elsevier Ltd. All rights reserved.
PY - 2016/10/20
Y1 - 2016/10/20
N2 - BACKGROUND: Refractoriness of cardiac cells limits maximum frequency of electrical activity and protects the heart from tonic contractions. Short refractory periods support major arrhythmogenic substrates and augmentation of refractoriness is therefore seen as a main mechanism of antiarrhythmic drugs. Cardiomyocyte excitability depends on availability of sodium channels, which involves both time- and voltage-dependent recovery from inactivation. This study therefore aims to characterise how sodium channel inactivation affects refractoriness in human atria.METHODS AND RESULTS: Steady-state activation and inactivation parameters of sodium channels measured in vitro in isolated human atrial cardiomyocytes were used to parameterise a mathematical human atrial cell model. Action potential data were acquired from human atrial trabeculae of patients in either sinus rhythm or chronic atrial fibrillation. The ex vivo measurements of action potential duration, effective refractory period and resting membrane potential were well-replicated in simulations using this new in silico model. Notably, the voltage threshold potential at which refractoriness was observed was not different between sinus rhythm and chronic atrial fibrillation tissues and was neither affected by changes in frequency (1 vs. 3Hz).CONCLUSIONS: Our results suggest a preferentially voltage-dependent, rather than time-dependent, effect with respect to refractoriness at physiologically relevant rates in human atria. However, as the resting membrane potential is hyperpolarized in chronic atrial fibrillation, the voltage-dependence of excitability dominates, profoundly increasing the risk for arrhythmia re-initiation and maintenance in fibrillating atria. Our results thereby highlight resting membrane potential as a potential target in pharmacological management of chronic atrial fibrillation.
AB - BACKGROUND: Refractoriness of cardiac cells limits maximum frequency of electrical activity and protects the heart from tonic contractions. Short refractory periods support major arrhythmogenic substrates and augmentation of refractoriness is therefore seen as a main mechanism of antiarrhythmic drugs. Cardiomyocyte excitability depends on availability of sodium channels, which involves both time- and voltage-dependent recovery from inactivation. This study therefore aims to characterise how sodium channel inactivation affects refractoriness in human atria.METHODS AND RESULTS: Steady-state activation and inactivation parameters of sodium channels measured in vitro in isolated human atrial cardiomyocytes were used to parameterise a mathematical human atrial cell model. Action potential data were acquired from human atrial trabeculae of patients in either sinus rhythm or chronic atrial fibrillation. The ex vivo measurements of action potential duration, effective refractory period and resting membrane potential were well-replicated in simulations using this new in silico model. Notably, the voltage threshold potential at which refractoriness was observed was not different between sinus rhythm and chronic atrial fibrillation tissues and was neither affected by changes in frequency (1 vs. 3Hz).CONCLUSIONS: Our results suggest a preferentially voltage-dependent, rather than time-dependent, effect with respect to refractoriness at physiologically relevant rates in human atria. However, as the resting membrane potential is hyperpolarized in chronic atrial fibrillation, the voltage-dependence of excitability dominates, profoundly increasing the risk for arrhythmia re-initiation and maintenance in fibrillating atria. Our results thereby highlight resting membrane potential as a potential target in pharmacological management of chronic atrial fibrillation.
U2 - 10.1016/j.yjmcc.2016.10.009
DO - 10.1016/j.yjmcc.2016.10.009
M3 - SCORING: Journal article
C2 - 27773652
VL - 101
SP - 26
EP - 34
JO - J MOL CELL CARDIOL
JF - J MOL CELL CARDIOL
SN - 0022-2828
ER -