Alkaline phosphatase and maltase activity in the embryonic chick intestine in culture: Influence of thyroxine and hydrocortisone☆

[摘要] Instripsofduodenumfrom14-daychickembryosexplantedintodefinedmedium,alkalinephosphatase(ALP)activityaccumulatedinthetissueatafasterratethaninvivoforabout48hr,butfailedtoincreasethereafter.Theadditionofthyroxine(T4)tothemediumat10−8MorlessbothenhancedtheearlyaccumulationandelicitedaverylargeincreaseinALPactivitycomparabletothatnormallyoccurringduringthelast2daysinovo.Activitywithphenylphosphate(PhP)wasmorestronglyaffectedthanthatwithβ-glycerophosphate(βGP),sothatthehighPhPβGPratioattainedinvivoat18dayswasreachedafter24hrinT4-supplementedmedium.Hydrocortisone(HC)evokedAPLactivityonlyslightlyabovethatinunsupplementedmediumandonlyduringthefirst48hrinculture,butitprecociouslyelevatedPhPβGPratiotothenormalmaximum.InthepresenceofT4orHC,maltaseactivityroseinexplantedstripsatthesamerateasintheintactduodenum,butitlaggedinunsupplementedmedium.Assayofthemediumrevealed,however,thatunderallconditionsofculturealargeamountofbothmaltaseandALPactivityhadbeenreleasedfromthetissue.ThiseffectwasespeciallypronouncedinthepresenceofT4,sothatexplantsandmediumtogetheraccumulatedALPandmaltaseequivalenttothehighpeaksofactivityfoundintheintactduodenumathatching.With10−8MT4,ALPactivitybegantoriseabovethatofcontrolexplantsafter8hr,withaccumulationinthemediumbeginningabout4hrlater.Combining2×10−6MHCwitharangeofT4concentrationsproducedgreaterthanadditiveeffects,particularlywithALP,butdidnotleadtoenhancedretentionofeitherenzymeinthetissuestrips.Prolactin,pentagastrin,andinsulinwerewithouteffectalone,butthelatterinhibitedtheeffectsofbothT4andHC.

[学科分类] 生物科学（综合）