Characterization of a Ca2+-activated Nonselective Cation Channel during Dedifferentiation of Cultured Rat Ventricular Cardiomyocytes

Characterization of a Ca2+-activated Nonselective Cation Channel during Dedifferentiation of... Cardiac hypertrophy is associated with electrical activity modifications, including sustained depolarization, that lead to a propensity for arrhythmias. The ionic currents underlying the sustained depolarization are not well defined. Similar modifications were reported on adult rat cardiomyocytes in primary culture undergoing dedifferentiation. Using the single-channel measurements on these cells, we identified the appearance of a Ca2+-activated nonselective cation channel (NSCCa) during the dedifferentiation process. In excised inside-out patches the channel presented a linear I/V relationship with a conductance of 26.5 pS. It was equally selective for Na+ and K+ and impermeable to Cl? and Ca2+ ions. The open probability increased with depolarization and with rise in intracellular calcium concentration. The channel activity was reduced by intracellular ATP and suppressed by flufenamic acid. Channel detection increased after incubation with a purinergic receptor agonist (ATPgS) or a PKC activator (PMA). Furthermore, occurrence of the channel developed during the culture. Absent at one day in vitro (d.i.v.), channel activity was present in 5, 46, 27 and 19% of patches after 4, 7, 14 and 21 d.i.v., respectively. We suggest that the channel may be associated with pro-arrhythmic signaling, in particular during the release of transmitters from autonomic nerve endings in the hypertrophied hearts. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png The Journal of Membrane Biology Springer Journals

Characterization of a Ca2+-activated Nonselective Cation Channel during Dedifferentiation of Cultured Rat Ventricular Cardiomyocytes

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Publisher
Springer-Verlag
Copyright
Copyright © 2002 by Springer-Verlag New York Inc.
Subject
Life Sciences; Biochemistry, general; Human Physiology
ISSN
0022-2631
eISSN
1432-1424
D.O.I.
10.1007/s00232-001-0180-4
Publisher site
See Article on Publisher Site

Abstract

Cardiac hypertrophy is associated with electrical activity modifications, including sustained depolarization, that lead to a propensity for arrhythmias. The ionic currents underlying the sustained depolarization are not well defined. Similar modifications were reported on adult rat cardiomyocytes in primary culture undergoing dedifferentiation. Using the single-channel measurements on these cells, we identified the appearance of a Ca2+-activated nonselective cation channel (NSCCa) during the dedifferentiation process. In excised inside-out patches the channel presented a linear I/V relationship with a conductance of 26.5 pS. It was equally selective for Na+ and K+ and impermeable to Cl? and Ca2+ ions. The open probability increased with depolarization and with rise in intracellular calcium concentration. The channel activity was reduced by intracellular ATP and suppressed by flufenamic acid. Channel detection increased after incubation with a purinergic receptor agonist (ATPgS) or a PKC activator (PMA). Furthermore, occurrence of the channel developed during the culture. Absent at one day in vitro (d.i.v.), channel activity was present in 5, 46, 27 and 19% of patches after 4, 7, 14 and 21 d.i.v., respectively. We suggest that the channel may be associated with pro-arrhythmic signaling, in particular during the release of transmitters from autonomic nerve endings in the hypertrophied hearts.

Journal

The Journal of Membrane BiologySpringer Journals

Published: Jul 1, 2002

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