Recombinant hTASK1 is an O(2)-sensitive K(+) channel

Area of Science:

• Molecular Biology
• Physiology
• Ion Channel Function

Background:

• Hypoxic inhibition of background potassium (K+) channels is vital for oxygen (O2) sensing in chemoreceptor tissues.
• Direct evidence for O2 sensitivity in any member of the K+ channel family has been lacking.
• Understanding O2-sensitive K+ channels is key to elucidating physiological O2 sensing mechanisms.

Purpose of the Study:

• To directly demonstrate O2 sensitivity in the human TASK1 (hTASK1) potassium channel.
• To investigate the role of hTASK1 in O2 sensing by chemoreceptor tissues.
• To provide the first direct verification of hTASK1's O2 sensitivity.

Main Methods:

• HEK293 cells were transfected with a pcDNA3.1-hTASK1 construct.
• hTASK1 expression was confirmed using RT-PCR and immunocytochemistry.
• Whole-cell K+ currents were measured, assessing sensitivity to extracellular pH and partial pressure of oxygen (pO2).

Main Results:

• hTASK1-expressing cells exhibited K+ currents highly sensitive to extracellular pH within the physiological range (IC50 ≈ 7.0).
• Reduction in pO2 from 150 to <40 mmHg rapidly and reversibly suppressed these pH-sensitive K+ currents.
• The O2-sensitive current magnitude was dependent on extracellular pH, indicating both signals act on the same channel.

Conclusions:

• This study provides the first direct evidence that the human TASK1 (hTASK1) potassium channel is sensitive to oxygen.
• These findings reinforce the role of hTASK1 as a key player in O2 sensing mechanisms within chemoreceptor tissues.
• hTASK1's dual sensitivity to pH and O2 positions it as a critical component in physiological O2 detection.