Screening for drugs blocking acetylcholine-activated ion channels and local anaesthetics with the isolated chick biventer cervicis preparation.
A convenient method for screening for drugs that block acetylcholine-activated ion channels, using the isolated chick biventer cervicis preparation is described. Since most of these drugs can only gain access to their site of action when the ion channel is in the open configuration, their effects are potentiated by prior treatment of the preparation with neostigmine. By preventing hydrolysis of acetylcholine, neostigmine enhances the possibility that ion channels will be in the open configuration. Potentiation of their neuromuscular blocking effects by neostigmine is apparently specific for drugs acting this way, other non-depolarizing neuromuscular blocking drugs are usually antagonized by neostigmine. The chick biventer cervicis preparation also contains a second set of accessible ion channels, the so-called voltage-gated channels in the nerve axons which are the site of action of local anaesthetic compounds. It has been observed that addition of local anaesthetics to the bathing solution causes an increase in the potential required to elicit indirect muscle contractions i.e. they induce a shift to the right of the voltage-response curve, a property which may be included in screening procedures with the isolated chick biventer cervicis preparation.
MacDonald
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Department of Pharmacology and Toxicology, University of Kuopio, Finland.
D000109:Acetylcholine / Q000502:physiology*; D000779:Anesthetics, Local; D000818:Animals; D002645:Chickens; D004353:Drug Evaluation, Preclinical; D066298:In Vitro Techniques; D007473:Ion Channels / Q000187:drug effects*; D008297:Male; D009132:Muscles / Q000187:drug effects*; D009388:Neostigmine / Q000494:pharmacology; D009466:Neuromuscular Blocking Agents / Q000494:pharmacology
D000779:Anesthetics, Local; D007473:Ion Channels; D009466:Neuromuscular Blocking Agents; D009388:Neostigmine; D000109:Acetylcholine