Quinine blocks the high conductance, calcium-activated potassium channel in rat pancreatic beta-cells

FEBS Lett. 1990 Jan 15;260(1):105-8. doi: 10.1016/0014-5793(90)80078-w.

Abstract

The [Ca2+]i-activated K+-channel, one of the 3 K+ -channels described in pancreatic beta-cells, is a high conductance, voltage-dependent K+-channel. Quinine, known to block [Ca2+]i-activated K(+)-channels in other cells, has been described to block the silent phase between the bursts of glucose-evoked electrical activity in mouse pancreatic beta-cells, and to inhibit K+ efflux from rat pancreatic islets. We report here that quinine blocks the [Ca2+]i-activated K(+)-channel in rat pancreatic beta-cells from the external side of the membrane. We also show that the blockade is characterized by fast flickering of the K(+)-channel between the open and closed state. Mean open and closed times within bursts were found to be exponentially distributed, suggesting that the blockade by quinine involves obstruction on the K(+) flow through the open to be exponentially distributed, suggesting that the blockade by quinine involves obstruction on the K+ flow through the open channel.

MeSH terms

  • Animals
  • Biological Transport / drug effects
  • Calcium / pharmacology*
  • Cell Membrane Permeability / drug effects
  • Cells, Cultured
  • Dose-Response Relationship, Drug
  • Electric Conductivity / drug effects
  • Glucose / metabolism
  • Ion Channel Gating / drug effects
  • Islets of Langerhans / drug effects*
  • Islets of Langerhans / metabolism
  • Potassium / metabolism
  • Potassium Channels / drug effects*
  • Potassium Channels / physiology
  • Quinine / pharmacology*
  • Rats

Substances

  • Potassium Channels
  • Quinine
  • Glucose
  • Potassium
  • Calcium