Influence of SKF-525A congeners, strophanthidin and tissue-culture media on desensitization in frog skeletal muscle.
1 Microelectrodes have been used to follow changes in membrane potential at end-plate regions of frog skeletal muscle fibres exposed to carbachol; the depolarizing drug was applied to narrow strips of muscle in a rapidly flowing solution containing relatively impermeant anions rather than chloride.2 During prolonged applications of carbachol (10 to 20 muM), the depolarization caused by the drug showed a gradual decline which was attributed to desensitization.3 Desensitization was little if at all affected by supplementing the external solution with factors present in tissue-culture media, or by treating the muscle with strophanthidin (25 muM).4 The rate of repolarization in the presence of carbachol (10 to 20 muM) was greatly increased by the SKF-525A congeners pipenzolate bromide (10 muM) and adiphenine hydrochloride (1 muM). The desensitization-enhancing action of these compounds is discussed.
D000818:Animals; D001561:Benzilates / Q000494:pharmacology*; D002217:Carbachol / Q000494:pharmacology; D003470:Culture Media; D046508:Culture Techniques; D004158:Diphenylacetic Acids / Q000494:pharmacology*; D004558:Electric Stimulation; D007700:Kinetics; D008564:Membrane Potentials / Q000187:drug effects; D008839:Microelectrodes; D009132:Muscles / Q000187:drug effects* / Q000294:innervation; D009467:Neuromuscular Depolarizing Agents / Q000494:pharmacology; D010115:Oxyphenonium / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology*; D011335:Proadifen / Q000031:analogs & derivatives* / Q000494:pharmacology; D011896:Rana temporaria; D013327:Strophanthidin / Q000494:pharmacology*; D013328:Strophanthins / Q000494:pharmacology*
D001561:Benzilates; D003470:Culture Media; D004158:Diphenylacetic Acids; D009467:Neuromuscular Depolarizing Agents; D010880:Piperidines; D013328:Strophanthins; D013327:Strophanthidin; D002217:Carbachol; D011335:Proadifen; D010115:Oxyphenonium