Developmental changes in embryonic enzyme patterns: The effect of oxidative substrates on lactic dehydrogenase in beating chick embryonic heart cell cultures

摘要

Duringthedevelopmentofthechickembryo,theLDHpatternoftheheartcellsremainsalmostunchanged,whileintheskeletalmusclecellsthesynthesisofM-LDHsubunitsbeginsatapproximately6a€“10daysofincubation.Whenplacedincellcultureinmonolayers,heartcellsbegintosynthesizeM-LDHsubunits,andthepatternofLDHwithinthesecellsshiftstocontainmuchmoreM4andM3HLDH.HeartcellsneversynthesizeM-LDHinanysignificantamountsifleftinovo.Citricacidcycleintermediates(KCA)andcoenzymeA(CoA)retardtheappearanceofthisnewlyacquiredsyntheticcapacity.TheLDHpatternseventuallybecomeidenticalwiththepatternsofthecontrols.RaisedpO2(95%O2:5%CO2)retardsM-LDHsynthesis,andundertheseconditionstheheartcells,unlikethecontrols,stablyproduceamuchsmallerproportionofM-LDHsubunits.Damagetothecellsduringdissociationandtrypsinizationleadingtoa€?leakya€?cellsmayaccountpartiallyforthealteredLDHpatternsseeninvitro.Itisproposedthatthecitricacidcycleintermediates,coenzymeA,andoxygenoperateatthelevelofthegeneineffectingthesechangesinthesyntheticpatternsoftheheartcellsinculture.