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Sodium current kinetics in cat atrial myocytes.
C H Follmer1, R E ten Eick, J Z Yeh
1Department of Pharmacology, Northwestern University, Chicago, IL 60611.
The Journal of Physiology
|March 1, 1987
Summary
This study reveals that the sodium (Na+) channel in cat atrial myocytes exhibits complex inactivation kinetics. Multiple inactivated states likely govern the sodium current
Area of Science:
- Cardiovascular Physiology
- Electrophysiology
- Molecular Cardiology
Background:
- Sodium current (Na+) is critical for cardiac action potential generation.
- Understanding Na+ channel kinetics is essential for comprehending cardiac electrophysiology.
Purpose of the Study:
- To investigate the kinetic properties of Na+ current in isolated adult cat atrial myocytes.
- To elucidate the mechanisms underlying Na+ current inactivation and recovery.
Main Methods:
- Utilized the single suction-pipette voltage-clamp technique.
- Performed single-pulse, double-pulse, and tail current measurements.
- Analyzed current-voltage and conductance-voltage relationships.
Main Results:
- Na+ current decay followed a second-order process.
- Steady-state inactivation curves showed asymmetry with an inflexion at -90 mV, suggesting multiple inactivation processes.
- Recovery from inactivation exhibited a complex sigmoid time course with distinct slow and fast components.
Conclusions:
- The kinetics of Na+ current inactivation in atrial myocytes are complex.
- Results are consistent with the presence of multiple inactivated states for the atrial myocyte Na+ channel.
- These findings contribute to a deeper understanding of cardiac sodium channel function.