The charge carried by single-channel currents of rat cultured muscle cells in the presence of local anaesthetics

J Physiol. 1983 Jun;339:663-78. doi: 10.1113/jphysiol.1983.sp014741.

Abstract

Acetylcholine-induced single-channel currents were measured in the presence of the lignocaine derivative QX222. Unit responses appeared as bursts of short current pulses as a result of the fast blocking action of the drug (QX222). The amplitude of the individual current pulses was not changed by the presence of the drug up to a concentration of 250 microM. The time integral of current during a burst, which for a sequential blocking model should be independent of drug concentration, decreased at concentrations of QX222 higher than 40 microM. The distribution of gap times within a burst could not be fitted by a single exponential for high concentrations of QX222. It is concluded that the simple sequential model of channel blockade does not apply for concentrations of QX222 higher than 40 microM.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetylcholine / pharmacology
  • Anesthetics, Local / pharmacology
  • Animals
  • Cells, Cultured
  • Dose-Response Relationship, Drug
  • Ion Channels / drug effects*
  • Lidocaine / analogs & derivatives*
  • Lidocaine / pharmacology
  • Membrane Potentials / drug effects
  • Models, Biological
  • Muscles / metabolism*
  • Rats
  • Time Factors

Substances

  • Anesthetics, Local
  • Ion Channels
  • QX-222
  • Lidocaine
  • Acetylcholine