从兴奋收缩耦联机制看心力衰竭正性肌力药物发展.ppt

从兴奋收缩耦联机制看心力衰竭正性肌力药物发展,田野教授哈医大二院心内科,提要,兴奋-收缩耦联机制正性肌力药的循证研究洋地黄制剂-肾上腺素能受体激动剂磷酸二酯酶抑制剂钙增敏剂新型正性肌力药的探索亚硝酰氢,兴奋-收缩耦联机制,Excitation-contraction(EC)couplingisatermcoinedin1952todescribethephysiologicalprocessofconvertinganelectricalstimulustomechanicalresponse.,SandowA(1952).Excitation-contractioncouplinginmuscularresponse.YaleJBiolMed25(3):176201.PMID130159500,Excitation-contractioncoupling,Cardiacexcitationcontractioncouplingistheprocessfromelectricalexcitationofthemyocytetocontractionoftheheart(whichpropelsbloodout).TheubiquitoussecondmessengerCa2+isessentialincardiacelectricalactivityandisthedirectactivatorofthemyofilaments,whichcausecontraction.,Bers,D.M.ExcitationContractionCouplingandCardiacContractileForceedn2(KluwerAcademic,Dordrecht,Netherlands,2019).,Cardiacexcitationcontractioncoupling,Cardiactissue,(Guinea-pigventricularcell),Cardiactissue,Cardiaccells,Theactionpotentialmovesthroughsarcolemma,Ttube,Ca2+-inducedCa2+-release,Ca+,Ca+,Ca+,Ca2+,Plb,Ca2+,Ca+,Ca2+,Ca2+,Ca2+,Ca2+,Ca2+,Ca2+,Ca2+,Ca+,Ca+,Ca+,Ca+,Ca2+,Ca+,Ca+,Ca+,Ca+,Ca2+,Ca+,Ca+,Ca2+,Ca+,Ca+,Ca+,Ca+,Ca+,Ca+,Ca+,Ca+,Ca+,Ca+,Ca+,Ca+,Ca2+,Ca+,Ca+,Ca+,Ca+,Ca+,Ca+,Ca+,Ca+,Ca+,Ca2+,Ca2+,Ca2+,Ca2+,Ca2+,Ca2+,Na+,Na+,Na+,Ca2+,SERCA,SR,RyR,L-TypeCa2+Channel,Na+/Ca2+Exchanger,Ca+,Sarcolemma,Ca2+,肌联蛋白（Titin）将粗肌丝与Z-线连接，维持肌原纤维的完整性和稳定性，保持舒张肌肉的静息张力，使粗肌丝处于肌小节的中央位置，使受牵拉的肌肉可恢复初始状态，以保证肌肉收缩时张力的输出。,Themolecularbasisformyocardialcontraction,Thinfilament(Actin,Tropom-yosin,Troponin)Thickfilament(Myosin)Otherproteins,Chien,K.R.,2019,F-actin,Z-line,Z-line,ThinFilamentProteins,GtoFactinMW42kDaTheblueandgreymoleculesareactinmonomers(MW42.000),KenC.Holmes:Max-Planck-Institute,肌动蛋白以两种形式存在,即单体和多聚体。单体的肌动蛋白是由一条多肽链构成的球形分子,又称球状肌动蛋白(globularactin,G-actin),外形类似花生果。肌动蛋白的多聚体形成肌动蛋白丝,称为纤维状肌动蛋白(fibrosactin,F-actin)。在电子显微镜下,F-肌动蛋白呈双股螺旋状,直径为8nm,螺旋间的距离为37nm。,LorenzmodelofF-actin.AsingleG-actinmonomerwithinter-actincontactsurfacesisshownontheright,theentireF-actinontheleft,ActinfilamentsaredynamicpolymerswhoseATP-drivenassemblyinthecellcytoplasmdrivesshapechanges,celllocomotionandchemotacticmigration.Actinfilamentsalsoparticipateinmusclecontraction.Thestructureofthefilamentisnotknownatatomicresolution,butseveralmodelswereproducedinthelaboratoryofKenHolmes(MPIformedicalresearch,Heidelberg,Germany)byrefinementagainstX-rayfiberdiffractiondata,Troponin,Head-to-tailoverlap,A,B,Takeda,S.etal.Nature424,3541,2019,Crystalstructureofhumancardiactroponin,TroponinC,C-Domain,N-Domain,CentralHelix,EachTnCdomaincontainstwomotifscalledEFhands,anditistheEFhandsthatdirectlybindcalciumions.Thus,theEFhandsareTnCswayofsensingthecalciumconcentration;at100nMcalcium(theusualcellularconcentration)theN-domainEFhandsareempty,butifthelocalconcentrationrisesto1mM,asitdoeswhenthemusclecontracts,alloftheEFhandbindcalcium.,KCa=3x105M-1Ca2+-specific,KCa=2x107M-1Ca2+-Mg2+sites,EFhands,Thickfilamentproteins,MYOSINMW480kDaFormsthickfilamentsHydrolysesATPInteractswithF-actin300-400myosinmoleculesper1filament,S1,150nm,Myosin,重链-helicalcoiled-coil,轻链,160nm,S1,S1-MolecularMotorofMuscleContraction,RLC,ELC,MyosinHead(S1)molecularmotorofmusclecontraction,RLC,ELC,ATPBindingSite,ActinBindingSite,ATP(Myosin)ADP+Pi+Energy,F-actin,Cross-bridgeActinInteraction,Gordonetal.2019,Regulationofthinfilamentincontraction,ABCDE,FromCraigandLehman,2019,JMB311,1027,Thereversiblebindingofcalciumtotroponinalterstheconformationofthethinfilament,therebyturningmusclecontractionONandOFF,Cross-bridgeSTATE:ThinfilamentSTATE:Relaxed(OFF)BLOCKEDCa2+Activated(WeakBinding)CLOSEDCa2+andMyosinActivated(Strongbinding)OPENThreepositionsofTropomyosinActivatedFilaments(blue:actinboundendofactivelycyclingcross-bridges),RegulationofMuscleContraction:,IntheabsenceofCa2+,theinteractionofmyosinwithactinandconsequentlycontractionisinhibited.UponreleaseofCa2+fromtheSR,theregulatory,Ca2+specificsitesofTnCbindCa2+exposingapatchofhydrophobicresidueslocatedintheN-terminaldomainofTnCandtheinteractionoftheTnCwithTnIandTnTcantakeplace.TheseinternalTninteractionspromotetranslocationoftheTnTmcomplexawayfromtheouterdomainoftheactinfilamentsenablingthecyclicinteractionbetweenmyosinheads(S1)andactin.Themyosinhead,anactinactivated-Mg2+-ATPasedependentmolecularmotor,bindstoactinandundergoesapowerstroke,aphenomenonresponsiblefortheinteractionbetweenthethickfilamentandthethinfilamentsandforcegeneration.,ATPaseCycle,1.AM+ATP,2.A+MATP,3.AMADPPi,4.AMADP+Pi,5.AM+ADP,Pi,ADP,Pireleaserate:10-20s-1,MuscleContraction,Pireleaserates:1.NoTm-Tn:1020s-1;2.+Tm-TnnoCa2+:0.1-0.2s-1;3.+Tm-Tn+Ca2+:1020s-1,Actin-myosininteraction,InvitromotilityassayshowingtheslidingofactinfilamentsoveramyosinsurfaceinitiatedbyflashphotolysisofcagedATP,(CliveR.Bagshaw),BersDM.Cardiacexcitation-contractioncouplingJ.Nature,2019,415(6868):198-205.,Excitation-contractioncoupling,Heartfailure,Ryanodinereceptor(RyR),PhosphorylationofRYRincrease,Ca2+leak,ATP-dependentpump,Phospholamban(PLB),InHF,ExpressionandactivationofSERCA2PhosphorylationofPLBExpressionof1ARATPsupply,uptake,Re-uptake,Store,Release,M,SR,SRCa2+sroredecrease,Ca2+transientdelay,TheSRCa2+store,1,2,3,4,5,1.ReducedCa+triggerthruL-typechannel,2.ReducedRyRfunction(CalciumleaksfromSR),3.DecreasedsensitivityofTN-CtoCa+,4.ReducedCa+uptakeduetolossofSERCAfunctionandincreasedPlb,5.IncreasedNa/Caexchangerfunction,OverviewofE-Ccouplingchangesinthefailingheart,正性肌力药的循证研究,Ancienttreatmentofheartfailure,洋地黄制剂（200years）,DigilispurpureaPurplefoxglove,WilliamWithering(1741-1799),MechanismofAction,DIG试验(2019),总死亡率是中性在3.5年的随访中，心衰恶化而死亡的危险性，地高辛组有降低趋势，地高辛显著降低了因心衰住院死亡的危险性28%（P0.01）。,TheEffectofDigoxinonMortalityandMorbidityinPatientswithHeartFailureNEng1Med,2019;336:525-533,总死亡率,TheEffectofDigoxinonMortalityandMorbidityinPatientswithHeartFailureNEng1Med,2019;336:525-533,因心衰住院死亡的发生率,TheEffectofDigoxinonMortalityandMorbidityinPatientswithHeartFailureNEng1Med,2019;336:525-533,Digitalisiswithoutquestionthemostvaluablecardiacdrugeverdiscoveredoneofthemostvaluabledrugsintheent-irepharmacopoeia.Theintroductionofdigitaliswasoneofthelandmarksinthehistoryofcardiacdisease.,Opie,H.L.DrugsfortheHeart.OrlandoFlorida:Grune74(supplII):II-39.,磷酸二酯酶抑制剂,ThedifferentformsorsubtypesofphosphodiesterasewereinitiallyisolatedfromratbrainsbyUzunovandWeissin1972andweresoonafterwardsshowntobeselectivelyinhibitedinthebrainandinothertissuesbyavarietyofdrugsThepotentialforselectivephosphodisteraseinhibitorsastherapeuticagentswaspredictedasearlyas1977byWeissandHait.Thispredictionmeanwhilehasprovedtobetrueinavarietyoffields.,Uzunov,P.andWeiss,BBiochim.Biophys.Acta284:220-226,1972,Weiss,B.andHait,W.N.:Ann.Rev.Pharmacol.Toxicol.17:441-477,1977.,代表药物为氨力农(amrinone)和米力农(milrinone)。增强心肌收缩力，降低后负荷，提高心肌舒张速率,PhosphodiesteraseInhibitors,MechanismofAction,PDEI为非强心甙非儿茶酚胺类强心药，通过抑制cAMP在心肌和平滑肌细胞的降解，而发挥正性肌力作用。,-ADR和PDEI的作用位点,(accordingtoLippincottsPharmacology,2019),PROMISE临床试验（1991）,NYHAIII、IV级，EF35%米力农1000例结果总死亡率28%心血管死亡率的危险性34%猝死危险69%亚组结论：心功能越差，危险性越高,试验提前终止,PackerM,etal.Effectofmilrinoneonmortalityinseverechronicheartfailure.NEnglJMed.1991;325:1468-1475.,TherapeuticUse,米力农尚不足以作为充血性心衰的首选强心剂和血管扩张剂只是作为重症心衰的辅助用药或洋地黄中毒患者的二次选择药物主要用于急性心衰,钙增敏剂,MCI-154、左西孟旦（levosimendan）是其中有代表性的药物。作用机制增加心肌TnC对Ca2的敏感性稳定Ca2-TnC构象直接增强肌球蛋白和肌动蛋白之间的相互作用,MechanismofAction,REVIVE-2研究(2019),REVIVE-2研究共入选600例心力衰竭患者,在常规治疗的基础上随机加用Levosimendan研究结果应用Levosimendan组心功能改善者比对照组多33%，心功能恶化者比对照组少30%,PackerM.AHAScientificSessions,Dallas,USA,November,2019.,PrimaryEndpoint(n=600),PackerM.AHAScientificSessions,Dallas,USA,November,2019.,33%,30%,SideEffects,研究发现通过增加钙敏感性的药物也可减慢心肌的舒张。这是由于增加了肌纤维对舒张时细胞内Ca2+的敏感性，使Ca2+从TnC的解离速度减慢，从而妨碍心肌的舒张，影响心室的充盈。,WhiteJ,LeeJA,ShahN,etal.DifferentialeffectsoftheopticalisomersofEMD53998oncontractionandcytoplasmicCa2+inisolatedferretcardiacmus-cleJ.CircRes,1993,73:61270.LeeJA,AllenDG.EMD53998sensitizesthecontractileproteinstocalciuminintactferretventricularmuscleJ.CircRes,1991,69:9272936.,TherapeuticUse,失代偿性急性心力衰竭，伴心输出量下降和高灌注压心脏术后心力衰竭（顿抑）急性心肌梗死后心力衰竭,新型正性肌力药的探索,亚硝酰氢,HNO是NO的去单电子产物，HN