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1、ActaPhysiologicaSinica,June25,2006,58(3):193-200193http://www.actaps.com.cnResearchPaperEffectofadrenomedullinontheactivityofbarosensitiveneuronsintherostralventrolateralmedullaofratsFANMing-Xin,LIXia,WANGJin,CAOYin-Xiang,SHENLin-Lin,ZHUDa-Nian*DepartmentofPhysiolo
2、gyandPathophysiology,ShanghaiMedicalCollegeofFudanUniversity,Shanghai200032,ChinaAbstract:Toinvestigatetheeletrophysiologicaleffectofratadrenomedullin(rADM)onbarosensitiveneuronsintherostralventrolat-eralmedulla(rVLM)anditspotentialmechanisms,theextracellularrecord
3、ingandmulti-barreliontophoresismethodswereused.Ofthe29barosensitiveneuronsintherVLM,20neuronsdemonstratedexcitatoryresponsetoiontophoreticallyappliedrADMandincreasedthefiringratefrom(10.8±2.7)spikes/sto(14.6±3.6),(19.8±4.7)and(31.9±6.4)spikes/s(P<0.05,n=20)atthecur
4、rentof30,60and90nA,respectively.Applicationofhumanadrenomedullin(22-52)[hADM(22-52)],aspecificantagonistofrADMreceptor,distinctlyattenuatedtheaugmentationoffiringrateinducedbyrADM—thefiringratewasincreasedby15.4%[(11.4±2.5)spikes/s,P<0.05,n=10].Anotherantagonist,hu
5、mancalcitoningene-relatedpeptide(8-37)[hCGRP(8-37)]hadnosignificanteffectonrADM-inducedexcitation.Other23barosensitiveneuronswererecordedtotesttheinfluenceofnitricoxidesynthase(NOS)inhibitorsontheexcitatoryeffectofrADM.In10neurons,7-NiNa(neuronalNOSinhibitor)decrea
6、sedthefiringratefrom(10.1±3.5)spikes/sto(7.5±2.5),(5.3±2.1)and(3.1±1.4)spikes/s(P<0.05,n=10)atthecurrentof10,20and40nA,respectively.TheexcitatoryeffectofrADM(60nA,30s)during7-NiNaapplicationwasnearlyeliminatedandthemagnitudeoffiringratewasincreasedonlyby17%ofthebas
7、allevel(6.2±1.9)spikes/s(P<0.05,n=7).Whileaminoguanidine(AG,iNOSinhibitor)increasedthefiringrateattherestinglevelfrom(11.5±5.1)spikes/sto(17.8±5.6),(22.5±6.3)and(29.1±6.4)spikes/s(P<0.05,n=8)atthecurrentof10,20and40nAin8barosensitiveneurons,respectively.WhenrADM(60
8、nA,30s)wasdeliveredduringAGiontophoresisperiod,thefiringratesignificantlyincreasedby60%ofthebasallevel[(22.5±6.3)spikes/s,n=5].Theseresultsindica