An oxygen-, acid- and anaesthetic-sensitive TASK-like background potassium channel in rat arterial chemoreceptor cells

J Physiol. 2000 May 15;525 Pt 1(Pt 1):135-42. doi: 10.1111/j.1469-7793.2000.00135.x.


The biophysical and pharmacological properties of an oxygen-sensitive background K+ current in rat carotid body type-I cells were investigated and compared with those of recently cloned two pore domain K+ channels. Under symmetrical K+ conditions the oxygen-sensitive whole cell K+ current had a linear dependence on voltage indicating a lack of intrinsic voltage sensitivity. Single channel recordings identified a K+ channel, open at resting membrane potentials, that was inhibited by hypoxia. This channel had a single channel conductance of 14 pS, flickery kinetics and showed little voltage sensitivity except at extreme positive potentials. Oxygen-sensitive current was inhibited by 10 mM barium (57% inhibition), 200 microM zinc (53% inhibition), 200 microM bupivacaine (55% inhibition) and 1 mM quinidine (105 % inhibition). The general anaesthetic halothane (1.5%) increased the oxygen-sensitive K+ current (by 176%). Halothane (3 mM) also stimulated single channel activity in inside-out patches (by 240%). Chloroform had no effect on background K+ channel activity. Acidosis (pH 6.4) inhibited the oxygen-sensitive background K+ current (by 56%) and depolarised type-I cells. The pharmacological and biophysical properties of the background K+ channel are, therefore, analogous to those of the cloned channel TASK-1. Using in situ hybridisation TASK-1 mRNA was found to be expressed in type-I cells. We conclude that the oxygen- and acid-sensitive background K+ channel of carotid body type-I cells is likely to be an endogenous TASK-1-like channel.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acidosis
  • Anesthetics / pharmacology
  • Animals
  • Barium / pharmacology
  • Bupivacaine / pharmacology
  • Carotid Arteries / metabolism*
  • Cells, Cultured
  • Chemoreceptor Cells / metabolism*
  • Halothane / pharmacology
  • Hydrogen-Ion Concentration
  • In Situ Hybridization
  • Nerve Tissue Proteins
  • Oxygen / pharmacology*
  • Patch-Clamp Techniques
  • Potassium Channels / metabolism*
  • Potassium Channels, Tandem Pore Domain*
  • Quinidine / pharmacology
  • RNA, Messenger / metabolism
  • Rats
  • Rats, Sprague-Dawley
  • Zinc / pharmacology


  • Anesthetics
  • Nerve Tissue Proteins
  • Potassium Channels
  • Potassium Channels, Tandem Pore Domain
  • RNA, Messenger
  • potassium channel subfamily K member 3
  • Barium
  • Quinidine
  • Zinc
  • Oxygen
  • Halothane
  • Bupivacaine