Intracellular Na+ activates a K+ channel in mammalian cardiac cells

Nature. 1984 May 24-30;309(5966):354-6. doi: 10.1038/309354a0.

Abstract

In a wide variety of cells, various intracellular agents, such as Ca2+, ATP and cyclic nucleotides, regulate ionic conductances of the membrane. In cardiac cells, the intracellular Na+ concentration [( Na+]i) frequently increases when a disturbance occurs in the electrogenic Na-K pump activity or the Na-Ca exchange mechanism. We have investigated a possible role of [Na+]i in controlling ion channels by using a patch-clamp method, and have found a K+ channel that is gated by [Na+]i greater than 20 mM, but not by the intracellular Ca2+ concentration (approximately 10(-4) M). We report here that the channel has a unitary conductance of 207 +/- 19 pS (n = 16) with K+ concentrations of 150 mM outside and 49 mM inside, and shows no detectable voltage-dependent kinetics. The Na+-activated K+ channel represents a novel class of ionic channel.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphate / pharmacology
  • Animals
  • Calcium / pharmacology
  • Guinea Pigs
  • Heart / physiology*
  • In Vitro Techniques
  • Ion Channels / physiology*
  • Kinetics
  • Membrane Potentials / drug effects
  • Potassium / metabolism*
  • Sodium / metabolism*
  • Sodium / pharmacology
  • Ventricular Function

Substances

  • Ion Channels
  • Adenosine Triphosphate
  • Sodium
  • Potassium
  • Calcium