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Modulation of cardiac inward rectifier K(+)current by halothane and isoflurane
A Stadnicka1, Z J Bosnjak, J P Kampine
1Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA. astadnic@mcw.edu
Anesthesia and Analgesia
|March 29, 2000
Summary
General anesthetics like halothane and isoflurane affect the inward rectifier potassium current (IKir) in heart cells. These volatile anesthetics modulate IKir in a voltage-dependent manner, potentially influencing heart rhythm.
Area of Science:
- Cardiovascular Physiology
- Anesthesiology
- Ion Channel Electrophysiology
Background:
- The precise cellular mechanisms of general anesthetics on cardiac ion channels remain unclear.
- The inward rectifier potassium current (IKir) is crucial for maintaining myocardial resting potential.
Purpose of the Study:
- To investigate the effects of halothane and isoflurane on cardiac IKir.
- To elucidate the voltage-dependent actions of these volatile anesthetics on IKir.
Main Methods:
- Whole-cell patch clamp technique on guinea pig ventricular myocytes.
- Concentration- and voltage-dependent analysis of anesthetic effects.
- Assessment of modulatory roles of magnesium and spermine.
Main Results:
- Halothane and isoflurane decreased inward IKir amplitude concentration- and voltage-dependently.
- Anesthetics increased outward current and shifted activation curves at positive potentials.
- Magnesium and spermine altered anesthetic effects, suggesting direct channel interaction.
Conclusions:
- Volatile anesthetics exhibit voltage-dependent modulation of cardiac IKir.
- Anesthetic interactions with the IKir channel protein are proposed.
- Differential modulation under altered rectification may explain anesthetic-induced dysrhythmias.