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Delayed rectifier potassium current (IK) in latent atrial pacemaker cells isolated from cat right atrium
1Loyola University of Chicago, Stritch School of Medicine, Department of Physiology, Maywood, IL 60153.
Pflugers Archiv : European Journal of Physiology
|February 1, 1994
Summary
This study reveals that latent pacemaker cells in cat atria possess a delayed rectifier potassium current (IK) activated by depolarization. This finding is crucial for understanding cardiac rhythm regulation.
Area of Science:
- Cardiology
- Electrophysiology
- Ion Channel Physiology
Background:
- Latent pacemaker cells in the atria play a role in cardiac rhythm.
- The delayed rectifier potassium current (IK) is essential for repolarization in cardiac cells.
Purpose of the Study:
- To characterize the delayed rectifier potassium current (IK) in latent pacemaker cells from the cat right atrium.
- To elucidate the activation kinetics and voltage-dependence of IK in these cells.
Main Methods:
- Whole-cell patch-clamp recording techniques were employed.
- Depolarizing and hyperpolarizing voltage clamp steps were used to elicit and analyze currents.
- A subtraction protocol was utilized to isolate IK tail currents.
Main Results:
- Depolarizing steps activated an outward current (IK) with sigmoidal time course and voltage-dependence.
- IK activation kinetics were described by a power function (n=2).
- IK tail currents showed a reversal potential of -78.2 mV in 5.4 mM [K+] and decayed with a time constant of 159 ms at -70 mV.
Conclusions:
- Latent atrial pacemaker cells express a functional delayed rectifier potassium current (IK).
- IK activation is dependent on membrane depolarization.
- These properties contribute to the electrophysiological profile of latent atrial pacemakers.