Temperature dependence of human ether-a-go-go-related gene K+ currents

Area of Science:

• Molecular and Cellular Physiology
• Cardiovascular Electrophysiology

Background:

• Voltage-gated human ether-à-go-go related gene (hERG) K(+) channels are essential for cardiac repolarization and preventing arrhythmias.
• hERG channels exhibit unique kinetics: slow activation/deactivation and rapid, voltage-dependent inactivation/recovery.

Purpose of the Study:

• To investigate the thermodynamic basis of hERG channel kinetics.
• To examine the effect of temperature on hERG channel activation and inactivation processes.

Main Methods:

• hERG channels were expressed in Chinese hamster ovary (CHO) cells.
• The impact of varying temperatures on channel activation and inactivation was studied using electrophysiological techniques, including action potential voltage clamps.

Main Results:

• Increased temperature shifted activation voltage dependence to more negative potentials and inactivation to more positive potentials.
• Higher temperatures accelerated activation, deactivation, inactivation, and recovery rates, with inactivation processes showing greater sensitivity.
• The magnitude of hERG current demonstrated significant temperature sensitivity.

Conclusions:

• Temperature profoundly influences the voltage dependence and kinetics of hERG channels.
• These findings explain the temperature sensitivity of hERG currents during cardiac action potentials.
• Results highlight that room temperature data cannot be reliably extrapolated to physiological temperatures (37°C) using simple scaling factors.