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1、ActaPhysiologicaSinica377Aug.1999,51(4),377～385INTERACTIONOFCONESIGNALSONL2TYPEHORIZONTAL3CELLINCARPRETINA:EXPERIMENTSANDMODELINGLIANGPEI2JI(KeyLaboratoryofNeurobiology,ShanghaiInstituteofPhysiology,ChineseAcademyofSciences,320Yue2YangRoad,Shanghai200031)ABSTRAC
2、TIntracellularrecordingsweremadefromtheluminositytypeconedrivenhorizontalcells(LHCs)intheisolatedcarpretinaandmodelanalysiswasperformedtoinvestigatepossiblemechanismsun2derlyingtheinteractionofdifferentconesignalsconvergingontothesecells.Itwasobservedthatagreenb
3、ackgroundlightenhancedtheLHC′sredresponse,andsuchenhancementwascloselyrelatedtotheactiva2tionofgreencones.Modelanalysisshowedthattheactivityofbothglutamate2andGABA2relatedpathwayswerepotentiatedduringgreenbackgroundillumination.GABAapplicationdidnotabolishtheres
4、ponseen2hancement.ItisspeculatedthattheextentoftheLHC′sresponseenhancementmaybedeterminedbythebalanceoftheincreasedactivitybetweenthefeedforwardandfeedbackpathways.Keywords:isolatedcarpretina;horizontalcell;interaction;modelanalysisInlowervertebrateretina,lumino
5、sitytypecone2drivenhorizontalcells(LHCs)arehyperpolar2izedbylightstimulus.Itiswellacceptedthatthehyperpolarizationresultsmainlyfromalight2in2[1～4]duceddecreaseoftheexcitatoryneurotransmitter(glutamate)releasedbyphotoreceptors.Therapiddecreaseinconcentrationofglu
6、tamateinthesynapticcleftmediatesabriefchangeincationchannel′sconductance,andthusresultsinaswiftdynamicsofLHC′smembranehyperpolarization.This,inturn,causesadecreaseinconcentrationoftheinhibitoryneurotransmitterγ2aminobutyricacid(GABA)releasedbyhorizontalcells,whi
7、chcontributestoregulatetheLHC′sresponsedynam2[5,6]icsbychangingtheactivityofanionchannelonthemembrane.Itwaspreviouslyreportedthatinteleostfish,redresponsesofLHCwereenhancedbygreenbackgroundillumination,whichwasthoughttobecausedbyaninteractionofdifferentconesigna
8、ls[7～12]convergingontoLHC.Sinceitwasobservedthataprecedinggreenconditioninglightenhanced[7,8]theLHC′sresponsetoasubsequentredstimulus,itwasthusassumedthattheinputfrom
