Enzymatic activity of differentiating muscle fibers: I. Development of phosphorylase in muscles of the domestic fowl☆

[摘要] Theontogenyoffibershasbeenstudiedbyfollowingchangesinphosphorylaseactivityofavianmuscle.Intheembryo,phosphorylasereactionsofbreast,heart,andlegmuscleareweak.Inbreastmuscle,theincreaseinphosphorylaseactivityisrapidafterhatchingandcanbeassociatedwithaconcomitantdevelopmentofthewhitefiber.Atmaturity,thepredominantfibershowsstrongphosphorylaseactivity.Thewhitefiber,unlikethered,isconcludedtobeahighlydifferentiatedfiberspecializedforanaerobicactivity.Theabnormalmusclesofdystrophicchickensshowreactionssimilartothenormalduringtheembryonicperiod.Atthistime,thewhitefiberhasnotyetbeguntodifferentiate.Alagintheformationoftheenzymeseenduringthefirstweekexovoindicatesaprolongedembryonicstateorafailureofembryocellstogrow.Withfurtherdevelopment,arapidincreaseinenzymeactivitydoesnotresultinphosphorlyaselevelsequaltothoseofnormaltissue.Instead,theactivityshowsadecreasefollowedbyavisibleimpairmentofmotorfunction.Itisemphasizedthattheabnormalityinenzymeactivityisnotedatadevelopmentalstagewhenred,white,andintermediatefibersarepresent.Alterationsinmorphologyandhistochemicaldistributionarecorrelatedwithchangesintotalphosphorylaseactivity.Commentsarealsomadeonlactatedehydrogenase,α-glycerophosphatedehydrogenase,andsuccinatedehydrogenasemeasuredhistochemically.

[学科分类] 生物科学（综合）