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Late Na channels in cardiac cells: the physiological role of background Na channels.

Publication ,  Journal Article
Zilberter YuI, ; Starmer, CF; Starobin, J; Grant, AO
Published in: Biophys J
July 1994

Two types of the late Na channels, burst and background, were studied in Purkinje and ventricular cells. In the whole-cell configuration, steady-state Na currents were recorded at potentials (-70 to -80 mV) close to the normal cell resting potential. The question of the contribution of late Na channels to this background Na conductance was investigated. During depolarization, burst Na channels were active for periods (up to approximately 5 s), which exceeded the action potential duration. However, they eventually closed without reopening, indicating the presence of slow and complete inactivation. When, at the moment of burst channel opening, the potential was switched to -80 mV, the channel closed quickly without reopening. We conclude that the burst Na channels cannot contribute significantly to the background Na conductance. Background Na channels undergo incomplete inactivation. After a step depolarization, their activity decreased in time, approaching a steady-state level. Background Na channel openings could be recorded at constant potentials in the range from -120 to 0 mV. After step depolarizations to potentials near -70 mV and more negative, a significant fraction of Na current was carried by the background Na channels. Analysis of the background channel behavior revealed that their gating properties are qualitatively different from those of the early Na channels. We suggest that background Na channels represent a special type of Na channel that can play an important role in the initiation of cardiac action potential and in the TTX-sensitive background Na conductance.

Duke Scholars

Published In

Biophys J

DOI

ISSN

0006-3495

Publication Date

July 1994

Volume

67

Issue

1

Start / End Page

153 / 160

Location

United States

Related Subject Headings

  • Time Factors
  • Tetrodotoxin
  • Sodium Channels
  • Rabbits
  • Purkinje Fibers
  • Membrane Potentials
  • Kinetics
  • Heart Ventricles
  • Heart
  • Cells, Cultured
 

Citation

APA
Chicago
ICMJE
MLA
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Zilberter YuI, ., Starmer, C. F., Starobin, J., & Grant, A. O. (1994). Late Na channels in cardiac cells: the physiological role of background Na channels. Biophys J, 67(1), 153–160. https://doi.org/10.1016/S0006-3495(94)80464-3
Zilberter YuI, A. O., C. F. Starmer, J. Starobin, and A. O. Grant. “Late Na channels in cardiac cells: the physiological role of background Na channels.Biophys J 67, no. 1 (July 1994): 153–60. https://doi.org/10.1016/S0006-3495(94)80464-3.
Zilberter YuI, Starmer CF, Starobin J, Grant AO. Late Na channels in cardiac cells: the physiological role of background Na channels. Biophys J. 1994 Jul;67(1):153–60.
Zilberter YuI, A. O., et al. “Late Na channels in cardiac cells: the physiological role of background Na channels.Biophys J, vol. 67, no. 1, July 1994, pp. 153–60. Pubmed, doi:10.1016/S0006-3495(94)80464-3.
Zilberter YuI, Starmer CF, Starobin J, Grant AO. Late Na channels in cardiac cells: the physiological role of background Na channels. Biophys J. 1994 Jul;67(1):153–160.
Journal cover image

Published In

Biophys J

DOI

ISSN

0006-3495

Publication Date

July 1994

Volume

67

Issue

1

Start / End Page

153 / 160

Location

United States

Related Subject Headings

  • Time Factors
  • Tetrodotoxin
  • Sodium Channels
  • Rabbits
  • Purkinje Fibers
  • Membrane Potentials
  • Kinetics
  • Heart Ventricles
  • Heart
  • Cells, Cultured