The functional differentiation of the small intestine. VIII. Regional differences in the alkaline phosphatases of the small intestine of the mouse from birth to one year☆

[摘要] 1.1.Thealkalinephosphataseactivityofthesmallintestineofthematuremouseishighestatthepyloricendoftheduodenumandfallssharplytoamuchlowerlevelinthejejunum.2.2.Thehighlevelofactivityintheduodenumisaccompaniedbyahighpreferenceforphenylphosphate(PhP)overβ-glycerophosphate(bGP).JejunalandilealphosphatasesshowapreferenceforbGPatmaximalactivitylevels.3.3.Inthepreweaningperiodalkalinephosphataseactivityisuniformthroughoutthesmallintestine.AllareashydrolyzebGPmoreeffectivelythanPhPatthistime.4.4.Thegreatincreaseinalkalinephosphataseactivitythatoccursintheduodenumduringthethirdpostnatalweek(i.e.,justbeforeweaning)involvestheappearanceofastrongpreferenceforPhP.Furtherkineticstudiessuggestthatthepreweaningincreaseinactivityintheduodenumrepresentsthesynthesisofanewenzymenotpreviouslypresentinsignificantquantity.5.5.Duringthethirdpostnatalweekjejunalandilealphosphataseactivitiesriseandfall.Thechangesareverysmallincomparisonwiththelargeincreaseoccurringconcomitantlyintheduodenum.6.6.Intheduodenum,exogenouscortisonebringsabouttheprecociousdevelopmentoflargequantitiesofaphosphatasehavingadecidedpreferenceforPhP.7.7.Inthejejunum,exogenouscortisonehasnoinfluenceonphosphataseactivity.Intheileumitfirstdepresses,thenelevates,phosphataseactivity,buttheinducedalterationsdonotparallelthenormalpatternofchangeinthepreweaningperiod.8.8.Histochemicalstudiesshowthatthemostactivephosphatasesarelocalizedinthemicrovillithroughouttheintestine.Surfacemeasurementsshowthatdifferencesinactivitycannotbeattributedtodifferencesinamountofmicrovilli-bearingsurfacealongthelengthoftheintestine.

[学科分类] 生物科学（综合）