血管紧缩素II 信号的稀释再配对eNOS 和禁止Nonendothelial 氮化物活动在糖尿病老鼠.docx
- 文档编号:92271
- 上传时间:2023-04-28
- 格式:DOCX
- 页数:25
- 大小:124.63KB
血管紧缩素II 信号的稀释再配对eNOS 和禁止Nonendothelial 氮化物活动在糖尿病老鼠.docx
《血管紧缩素II 信号的稀释再配对eNOS 和禁止Nonendothelial 氮化物活动在糖尿病老鼠.docx》由会员分享,可在线阅读,更多相关《血管紧缩素II 信号的稀释再配对eNOS 和禁止Nonendothelial 氮化物活动在糖尿病老鼠.docx(25页珍藏版)》请在冰点文库上搜索。
血管紧缩素II信号的稀释再配对eNOS和禁止Nonendothelial氮化物活动在糖尿病老鼠
AttenuationofAngiotensinIISignalingRecoupleseNOSandInhibitsNonendothelialNOXActivityinDiabeticMice
Jeong-HoOak,andHuaCai
FromtheDivisionofMolecularMedicine,DepartmentsofAnesthesiologyandMedicine,CardiovascularResearchLaboratories,DavidGeffenSchoolofMedicine,UniversityofCaliforniaLosAngeles,LosAngeles,California
AddresscorrespondenceandreprintrequeststoHua"Linda"Cai,MD,PhD,DivisionofMolecularMedicine,DepartmentsofAnesthesiologyandMedicine,CardiovascularResearchLaboratories,DavidGeffenSchoolofMedicine,UniversityofCaliforniaLosAngeles,650CharlesE.YoungDr.South,SuiteBH550CHS,LosAngeles,CA90095.E-mail:
hlcai@ucla.edu
Abbreviations:
AngII,angiotensinII;AT1R,AngIIreceptortype1;CMH,methoxycarbonyl-2,2,5,5-tetramethyl-pyrrolidine;DETC,diethyldithiocarbamicacid;DHE,dihydroethidium;DHFR,dihydrofolatereductase;eNOS,endothelialnitricoxidesynthase;ESR,electronspinresonance;H4B,tetrahydrobiopterin;L-NAME,N-nitro-L-argininemethylesterhydrochloride;NOX,NAD(P)Hoxidase;ROS,reactiveoxygenspecies;STZ,streptozotocin;VSMC,vascularsmoothmusclecell
ABSTRACT
TOP
ABSTRACT
RESULTS
DISCUSSION
RESEARCHDESIGNANDMETHODS
REFERENCES
AngiotensinII(AngII)levelsareincreasedinpatientswithdiabetes,butmechanismsunderlyingitscontributiontodiabeticvasculardiseasesareincompletelyunderstood.Werecentlyreportedthatinaorticendothelialcells,AngIIinducesendothelialnitricoxidesynthase(eNOS)uncouplingtoproducesuperoxide(O2·–)ratherthannitricoxide(NO·),uponlossofthetetrahydrobiopterin(H4B)salvageenzymedihydrofolatereductase(DHFR).Here,wefoundthatstreptozotocin-induceddiabeticmicehadamarkedincreaseinaorticO2·–production,whichwasinhibitedbyN-nitro-L-argininemethylesterhydrochloride,indicatinguncouplingofeNOS.AngIIreceptortype1blockercandesartanorACEinhibitorcaptoprilmarkedlyattenuatedeNOS-derivedO2·–andhydrogenperoxideproductionwhileaugmentingNO·bioavailabilityindiabeticaortas,implicatingrecouplingofeNOS.O2·–andNO·productionwerecharacteristicallyandquantitativelymeasuredbyelectronspinresonance.DHFRexpressionwasdecreasedindiabeticaortasbutsignificantlyrestoredbycandesartanorcaptopril.EitheralsoimprovedvascularH4Bcontentandendothelium-dependentvasorelaxationindiabetes.Rac1-dependentNAD(P)Hoxidase(NOX)activitywasmorethandoubledintheendothelium-denudeddiabeticaortasbutwasattenuatedbycandesartanorcaptopril,indicatingthatNOXremainsactiveinnonendothelialvasculartissues,althoughuncoupledeNOSisresponsibleforendothelialproductionofO2·–.ThesedatademonstrateanovelroleofAngIIindiabeticuncouplingofeNOSandthatAngII–targetedtherapyimprovesendothelialfunctionviathenovelmechanismofrecouplingeNOS.DualeffectivenessonuncoupledeNOSandNOXmayexplainthehighefficacyofAngIIantagonistsinrestoringendothelialfunction.
Productionofreactiveoxygenspecies(ROS)isincreasedinbothtype1andtype2diabetes,contributingnotonlypartiallytoetiologyofdiabetes(1–4),butalsosignificantlytodiabeticaccelerationofvasculardiseases(2,4–9).OneimportantmechanismforROS-inducedvasculardamageisoxidativedegradationofnitricoxide(NO·).ThisleadstoendothelialdysfunctionthatischaracterizedbyalossinNO·-dependentvasodilatation(6,9).Endothelium-dependentvasodilatationisimpairedindiabetes,andthiscanbesignificantlyreversedbysuperoxidedismutaseortheantioxidantvitaminC(10–12).Indiabeticcoronaries,ROSalsohinderendothelium-dependenthyperpolarizingfactor–mediatedvasodilatation(13).Whatremainstobefullyelucidatedistheenzyme(s)responsibleforproductionofROSindiabetes.RecentstudiesdemonstratethatvascularNAD(P)Hoxidase(NOX)servesasthepredominantsourceofROSinthediseasedbloodvessels(9,14).Uncoupledendothelialnitricoxidesynthase(eNOS),however,couldbeanotherimportantsourceofROS(seebelow)inthediabeticendothelium(15),likelydownstreamofNOX(14,16).MitochondriaasROSresourceshavebeeninvestigatedinnonvascularcellsindiabetes.RecentstudiessuggestthattheremightbecrosstalksbetweendifferentenzymaticsourcesofROS,resultinginROS-dependentself-propagation(16).
ByproducingNO·toinactivatesuperoxide(O2·–)anditsderivatives,eNOSnormallyfunctionsasapotentantioxidantenzymeinthevasculature.Togetherwithotheranti-inflammatoryandantithromboticpropertiesofNO·,thisantioxidantroleofeNOSisessentialforprotectionagainstendothelialdysfunction.Underpathologicalconditions,however,eNOScantransformintoapro-oxidant,generatingO2·–ratherthanNO·.This"uncoupling"ofeNOSoccursnotonlyin"traditional"vasculardiseasessuchashypertensionandatherosclerosis(14,17–19),butalsoindiabeticbloodvessels(15).ThenextobviousquestionisthenwhatisthecommonmechanismthatinducesuncouplingofeNOSindifferentvasculardiseases?
AngiotensinII(AngII)isacirculatingvasoconstrictivehormonewhoseproductionisoftenelevatedinpatientswithhypertensionandhypercholesterolemia.InfusionofAngIIinapolipoproteinE–deficientorLDLreceptor–deficientmicedramaticallyacceleratedatherogenesis(20–22).Ofimportance,productionofAngIIisalsoincreasedinpatientswithdiabetes,particularlythosewithhypertensionandrenaldysfunction(23,24).Itisgenerallybelievedthathyperglycemiaintheearlystagesofdiabetesinduceshyperfiltrationandnatriuresis,andthisactivatesAngIIsynthesisasacompensatorymechanismtomaintainnormalbloodpressure(25,26).HighglucosealsopotentlyupregulatesexpressionoftheAngIIreceptortype1(AT1R)(27).ThisresponsecouldsensitizevascularcellstoAngII.ItisthusrationaltohypothesizethatAngIImaymediatecommonpathologicalmechanismsinvolvedinthedevelopmentofdifferentvasculardiseases.OnepossibletargetcouldbeeNOS.
Werecentlyreportedthatinculturedaorticendothelialcells,AngIIinducesNOX-dependentuncouplingofeNOS(19).Dihydrofolatereductase(DHFR)isthekeyenzymeresponsibleforsalvationoftheeNOScofactortetrahydrobiopterin(H4B)fromitsinactive,oxidizedform.NormalendothelialDHFRisrequiredforbasalendothelialH4BandNO·bioavailability(19).AngII,however,caninduceDHFRdeficiencyviahydrogenperoxide(H2O2)–dependentmechanisms,resultinginalossofH4Band,consequently,theuncouplingofeNOS.Inkeepingwiththis,scavengingH2O2oroverexpressingDHFRwaseffectiveinrestoringNO·productionfromeNOSwhileeliminatingeNOS-derivedO2·–production(19).InviewofthepotentialsignificanceofAngIIindiabeticvasculardisease,inthecurrentstudy,weinvestigatedwhetherAngIIisinvolvedindiabeticuncouplingofeNOSinvivo,andwhetherattenuationofAngIIsignalingwithAT1RblockercandesartanorACEinhibitorcaptopriliseffectiveinrecouplingeNOStoimproveendothelialfunction.Tissue-specific,differentialcontributiontototaldiabeticvascularO2·–productionofuncoupledeNOSandNOXwasalsoexamined.
RESULTS
TOP
ABSTRACT
RESULTS
DISCUSSION
RESEARCHDESIGNANDMETHODS
REFERENCES
Hyperglycemiainstreptozotocin-induceddiabeticmice.
Diabeticmicewerecreatedbystreptozotocin(STZ)administrationasdescribedindetailinRESEARCHDESIGNANDMETHODS.Ondayofharvest(7th–8thdayafterinitialSTZinjection,samehereafter),bloodglucosewaselevatedto452.0±15.1mg/dlindiabeticmiceversus148.4±3.2mg/dlintheC57BL6controls(Fig.1).Candesartan(100mg·kg–1·day–1,samehereafter)orcaptopril(100mg·kg–1·day–1,samehereafter)treatmentsinceday4hadnosignificanteffectonSTZinductionofhyperglycemia(522.5±14.6or478.3±14.6mg/dl,respectively;Fig.1).Fortheentirestudyperiod,miceweremonitoredandfoundcomfortablewithoutanysignsofseverelossinbodyweight.
Viewlargerversion(45K):
[inthiswindow]
[inanewwindow]
FIG.1.Bloodglucoselevels.Ondayofharvest,bloodwascollectedfromtailveinforglucoseanalysisforeachmouse,usingOneTouchglucosemonitorandmatchingstripes.P<0.05vs.control,ANOVA,n=36.
UncouplingofeNOSindiabetes.
DiabeticaortasshowedamarkedincreaseintotalROSproduction,detectedbydihydroethidium(DHE)fluorescence(Fig.2A).WhereasN-nitro-L-argininemethylesterhydrochloride(L-NAME)(100µmol/l;inhibitorofNO·synthase)increasedROSproductioninthecontrolsbecauseofscavengingofNO·fromcoupledeNOS,italmostcompletelyattenuatedROSinthediabeticmice,stronglysuggestinguncouplingofeNOS(Fig.2A).Aorticproductionofsuperoxideanion(O2·–)wasalsodetectedspecificallyusingelectronspinresonance(ESR)andacell-permeableO2·–-specificspintrapmethoxycarbonyl-2,2,5,5-tetramethyl-pyrrolidine(CMH)(fordetails,seeRESEARCHDESIGNANDMETHODS).AsshownbyrepresentativeESRspectrainFig.2BandquantitativedatainFig.2CandD,aorticO2·–productionwasmorethandoubledindiabeticmice(3.3±1.6vs.7.0±2.6nmol/lpermin/mgwetwtaortaforcontrolvs.diabeticmice),andthisresponsewasattenuatedtonearbaselinebyL-NAME.L-NAMEdidnotpotentiatedetectableO2·–incontrolmice,likelybecauseoftherapiddegradationofO2·–intootherspecies,becauseL-NAMEdidenhancetotalROSproductiondetectedbyDHE.Takentogether,bydirectlymeasuringL-NAME–sensitiveaorticROSingeneralandO2·–productionspecificallyandquantitatively,thesedataclearlydemonstrateth
- 配套讲稿:
如PPT文件的首页显示word图标,表示该PPT已包含配套word讲稿。双击word图标可打开word文档。
- 特殊限制:
部分文档作品中含有的国旗、国徽等图片,仅作为作品整体效果示例展示,禁止商用。设计者仅对作品中独创性部分享有著作权。
- 关 键 词:
- 血管紧缩素II 信号的稀释再配对eNOS 和禁止Nonendothelial 氮化物活动在糖尿病老鼠 血管 紧缩 II 信号 稀释
链接地址:https://www.bingdoc.com/p-92271.html