The actions of some anticholinesterase drugs on skeletal muscle in culture

Abstract The actions of the anticholinesterase drugs, physostigmine, neostigmine and diisopropylfluorophosphate (DFP) on chick embryonic skeletal muscle in culture were studied. None of the anticholinesterases potentiated depolarization responses to acetylcholine. In high concentrations neostigmine and physostigmine produced depolarization. The neostigmine-induced, but not the physostigmine-induced, depolarization was antagonized by tubocurarine. DFP caused an increase in the rate of repolarization during the presence of a cholinomimetic. It is concluded that the cholinesterase present in cultured muscle fibres does not have a physiological role in hydrolysing acetylcholine and that physostigmine and DFP have an action at the ionic channels that are linked to the cholinoreceptor.