Effects of spinal cord and substrate on acetylcholinesterase in chick embryonic skeletal muscle☆

[摘要] Thedevelopmentalchangesinthespecificactivitiesoftheenzymesacetylcholinesterase(AChE)andcholinesterase(ChE)inembryonicchickskeletalmusclehavebeendeterminedfromtheseventhdayofincubationtohatching.EvidencewaspresentedbymeansofdenervationstudiesthatpriortothesixteenthdayofdevelopmenttheAChEofthismuscletissueismyogenicinorigin.AdefinitechangeintheshapeofthedevelopmentalcurveofAChEafterthefifteenthdaywasinterpretedintermsofmotorendplateformationinthemusclefibers.Acetyl-β-methylcholine(methacholine),asubstrateofAChE,wasshowntoraisetheactivityoftheenzymeoverthatofcontrolsinprimarymonolayerculturesof8-dayembryonicmusclecells,butthiseffectcannotberegardedasatrue“inductive”response.Onlyaftertheleveloftheenzymehaddroppedtoalowlevelinthecultures,after3–4serialtransfers,didthissubstrateinduceAChE,andtheresponsewassmall.Spinalcordfrom4-daychickembryosaddedtomonolayerculturesofmuscletissueenhancedgrowthslightly,butdepressedthespecificactivityofAChE.Thisdepressionwaspartiallyovercomebyaddingthesubstratemethacholine.ItisconcludedthatsubstrateinductionisnotaprimarymechanismforthecontrolofAChEinembryonicchickskeletalmuscleandthatembryonicspinalcordexertsitsinfluenceupondevelopingmusclebyfactorsotherthanstationarylevelsofacetylcholine.

[学科分类] 生物科学（综合）