The charge carried by single-channel currents of rat cultured muscle cells in the presence of local anaesthetics.
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.
D000109:Acetylcholine / Q000494:pharmacology; D000779:Anesthetics, Local / Q000494:pharmacology; D000818:Animals; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D007473:Ion Channels / Q000187:drug effects*; D008012:Lidocaine / Q000031:analogs & derivatives* / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects; D008954:Models, Biological; D009132:Muscles / Q000378:metabolism*; D051381:Rats; D013997:Time Factors
D000779:Anesthetics, Local; D007473:Ion Channels; C006072:QX-222; D008012:Lidocaine; D000109:Acetylcholine