心肌缺血预处理课件.ppt

1、2020年10月2日1Ischemic preconditioning(PC)is the phenomenon describing protection of the heart against reperfusion injury following prolonged ischemia,by virtue of prior short episode(or episodes)of ischemia and reperfusion.2020年10月2日2An analogous phenomenon of cardiac protection against reperfusion in

2、jury by pre-administration of a drug is called drug-induced PC.We have developed a family of drugs that can do it.2020年10月2日3IschemiaR1R2Stabilization10 minReperfusion20 minPc 1 Pc 2 Pc 3R3The System:Isolated rat heartThe procedure:Three episodes of 2 globalischemia separated by 3 reperfusion PC2020

3、年10月2日4Two windows of protection by ischemic PC have been identified:1 3 hours following PC,and 24 hour following PC.We work with the isolated rat heart,and will focus on the first window.2020年10月2日5Cardiac Function without and with PC has been studied.Below the following parameters are presented:DP

4、=PSP-EDP+dP/dt EDPother parameters not shown2020年10月2日6Developed Pressure(DP)(%of pre-ischemic value)Versus Ischemic Time Preconditioning(PC)806040200020406080100120ControlCPCDuration Ischemia(min)Dev.Pressure(recovery%)2020年10月2日7+dP/dt(%)Versus Ischemic Time Preconditioning(CPC)8060402000204060801

5、00120ControlCPCDuration of Ischemia(min)+dP/dt(recovery%)2020年10月2日8EDP(mmHg)Versus Ischemic Time Preconditioning(CPC)806040200020406080100ControlCPCDuration of Ischemia(min)EDP(mmHg)2020年10月2日9BIOCHEMISTRY Biochemical parameters of the heart tissue:a similar protection was observed for ATP,energy c

6、harge,ascorbate and other parameters.in the coronary flow:leakage into the CF of cellular metabolites:2020年10月2日10HPLC Analysis of the First 10-CFFsFollowing 35 Global Ischemia PC010203040506070Control:ischemia of 35-no PCPreconditioning followed by 35 ischemiaS SAS SPUAInoAA2020年10月2日11Currently Pr

7、oposed Mechanisms of Protection by PCThe detailed understanding of the mechanism of PC is still under investigation.Several possibilities have been suggested including:adenosine activation;preservation of high-energy phosphates;washout of metabolites;role of Ca+-channels;2020年10月2日12increase in anti

8、oxidants activity;synthesis of heat-shock proteins,G-proteins;nitric oxide production;role of K+-channels;role of PKCWE HAVE BEEN STUDYING THE ROLES OF IRON,COPPER AND FREE RADICALS IN ISCHEMIA AND OBTAINED INDICATIONS FOR THEIR INVOLVEMENT IN CARDIAC PC2020年10月2日13ROS-Reactive Oxygen Species-in rep

9、erfusion injury The formation of ROS from relatively less reactive species is mediated by redox-active metal ions.Circumstantial evidence suggests a causative role for newly mobilized redox-active iron in tissue injury.2020年10月2日14Two lines of evidence support this idea:Inclusion of iron chelators i

10、n the perfusate has been shown to protect against tissue injury following ischemia.Addition of iron or copper to the perfusate facilitated injury in hearts subjected to ischemia and reperfusion.2020年10月2日15McCords Scheme for Myocardial Damage Following Ischemia and Reperfusion reoxygenationIschemia2

11、020年10月2日16McCord scheme Ischemia reoxygenationATP AMPAdenosine InosineHypoxanthine2020年10月2日17McCord scheme Ischemia reoxygenationATP AMPAdenosine InosineHypoxanthineXanthinedehydrogenaseXanthineoxidase2020年10月2日18McCord scheme Ischemia reoxygenationATP AMPAdenosine InosineHypoxanthineXanthinedehyd

12、rogenaseXanthineoxidaseCa2+Protease2020年10月2日19McCord scheme Ischemia reoxygenationATP AMPAdenosine InosineHypoxanthineXanthinedehydrogenaseXanthineoxidaseO2Ca2+ProteaseO22020年10月2日20McCord scheme-modified Ischemia reoxygenationATP AMPAdenosine InosineHypoxanthineXanthinedehydrogenaseXanthineoxidase

13、O2Ca2+ProteaseO2 OH2020年10月2日21McCord scheme-modified Ischemia reoxygenationATP AMPAdenosine InosineHypoxanthineXanthinedehydrogenaseXanthineoxidaseO2Ca2+ProteaseO2 OHCu/Fe2020年10月2日22Fe(II)+H2O2 Fe(III)+OH-+OHFenton Reaction2020年10月2日23Haber Weiss Reactionor Superoxide-Driven Fenton ReactionO2 +Fe(

14、III)O2 +Fe(II)(1)Fe(II)+H2O2 Fe(III)+OH-+OH(2)O2+H2O2 OH +OH-+O2(3)-2020年10月2日24Fe and Cu Fenton and Haber-Weiss reactions for copper are also valid.copper might prove even more important than iron in catalyzing such a reaction,and as mediators of tissue injury(conc,mobility and reactivity).2020年10月

15、2日25Cardiac injury well correlated with the level of Fe/Cu mobilization from the heart tissue to the coronary flow(CF).It was further proposed that Fe/Cu levels in the CF can serve as predictive criteria for the degree of cardiac injury2020年10月2日26MOBILIZATION OF Fe/Cu into CORONARY FLOW FRACTIONSCF

16、F#1 versus TOTAL Fe/Cu02040608010012014018 3560CFF#9876543210Fe(ng/ml)2020年10月2日27TOTAL Fe levels in the CFFs#1 Versus Ischemic Time Preconditioning70605040302010020406080100120140ControlPCDuration of IschemiaFe(ng/ml)2020年10月2日28TOTAL Cu levels in the CFFs#1 Versus Ischemic Time Preconditioning7060

17、504030201001020304050ControlPCDuration of IschemiaCu(ng/ml)2020年10月2日291825354552600.000.250.500.751.001.251.501.75ControlCPCDuration of Ischemia(min)Fe/Protein706050403020100123Duraton of Ischemia min)Fe/Protein(Contr/CPC)2020年10月2日30Isolated Rat Heart(Langendorff)R1R2IschTime:10 2 3 2 3 2 3 18-60

18、20StabilReperfusionPc 1 Pc 2 Pc 3R3CFF#0 1,2 1,2 1,2 1.10 Collection time:-10 3 0 3 0 3 0-1 2020年10月2日31Iron in the CFFs following Global Ischemia without PC02040608010012014018 3560CFF#9876543210Fe(ng/ml)2020年10月2日32Iron in CFFs FollowingPC and Global Ischemia03570105140CFF#0 1 2 1 2 1 2 pc1 pc2 pc

19、31 2 3 4 5 6 7 8 9 102020年10月2日33Copper in the CFFs following Global Ischemia 109876543210010203040CFF#18 3560Cu(ng/ml)2020年10月2日34Copper in The CFFs Following Preconditioning and Global Ischemia 010203040CFF#pc1 pc2 pc31 2 3 4 5 6 7 8 9 10 0 1 2 1 2 1 2Cu(ng/ml)2020年10月2日35Ischemia 18Ischemia 35Isc

20、hemia 6001-11-22-12-23-13-24020100300408012016012345678910123456789100408012016001-11-22-12-23-13-2040801201601234567891040201003012345678910402010030Cu(ng/ml)Fe(ng/ml)2020年10月2日36TOTAL Fe/Cu versus LAMP (LIP)Is it the total Fe/Cu that plays a role in mediation of injury?“LAMP”-the LAbile transition

21、Metals Pool is the active fraction,and is important!The over-estimated values in the literatureHow can we quantitate LAMP?2020年10月2日37CFF-LAMP Mediated Conversion of Salicylate to 2,5-DHBA7060504030201001020304050ControlPCDuration of Ischemia2,5-DHBA(ng/ml)2020年10月2日38CFF-LAMP Mediated Conversion of

22、 Salicylate to 2,3-DHBA 70605040302010-551525354555ControlPCDuration of Ischemia2,3-DHBA(ng/ml)2020年10月2日39Three levels of mobilized metal ions:PC phaseprolonged ischemia following PCprolonged ischemia2020年10月2日40Ferritin Levels in Heart Tissue and in Coronary Flow(CF)following 35 ischemia HEART TIS

23、SUE Total Ft inFt/ProteinFe/Protein CF (m mg/mg)(m mg/mg)(m mg)Ischemia/reperfu-sion group(80)0.54+0.07 0.167 1.30+0.14PC/Ischemia andReperfusion group(80)0.90+0.13*0.198 0.73+0.11Normal-Perfusion group (80)0.64+0.10 0.196 0.19+0.052020年10月2日41Iron Level in Heart Tissue Ferritin (m mg/m mg)Experimen

24、tal GroupFe in Ferritin (m mg/m mg)Ischemia group(80 min)0.31+0.04PC group(80 min)0.22+0.04*Normal perfusion group(80)0.32+0.04PC (25 min)0.30+0.012020年10月2日42Three levels of mobilization of iron:high levels are associated with tissue injury.The PC phase:low levels of mobilized iron(and copper)and n

25、o damage.Removal of the inhibitory control of protein synthesis through the conversion of IRP to Aconitase.2020年10月2日43 FerritinFerritin is an intracellular iron binding protein,able to store about 4,000-4,500 iron atoms per molecule.Under normal conditions the amount of iron in heart Ferritin is ab

26、out 1,500-2,500 iron atoms.2020年10月2日44FerritinSullivan(1981)and Salonen et al.(1992)reported an association between the increase of iron stores and the risk of myocardial infarction.They demonstrated an important role for the increase of ferritin in ischemic heart disease.Magnusson et al.(1994)and

27、Enbergs et al(1998),on the other hand,did not find such a correlation between ferritin levels and myocardial infarction.Recent publications(1997-2000)tend to support the claim that ferritin is a marked risk factor for AMI.2020年10月2日45Does Ferritin Synthesis take place during or following PC?Is prote

28、in synthesis required for PC?Does it involve transcriptional or translational control?2020年10月2日46Ferritin synthesisWhite and Munro(1987)reported about rapid translational response to iron in rat liver:mRNA of both ferritin subunits was mobilized to polysomes.Tacchini et al.(1997)and Cairo et al.(19

29、98)showed that ischemia-reperfusion and oxidative stress lead to inhibition of IRP activity followed by activation of ferritin synthesis.2020年10月2日47Several studies have indicated that protein synthesis is required for PC.The PC effect was abolished only with cycloheximide,but not with actinomycin D

30、,indicating that PC is regulated at the post-transcriptional level.In another study:Inhibitors of protein synthesis have been used in the in vivo rabbit model.Neither cycloheximide nor actinomycin D did reverse the PC effect.The inhibition of protein synthesis was not complete(85%)and only one episo

31、de was applied(Thornton et al.,1990).2020年10月2日48 Our preliminary results indicate that PC is associated with accumulation of ferritin,and fits into the post-transcriptional regulation model.Translation of Ft could occur by taking advantage of Ft-mRNA that is present in the cells.2020年10月2日49Signali

32、ng with“LAMP”in PCDuring the PC phase small but reproducible levels of Fe/Cu are liberated from their proteins,and serve as intracellular and/or intercellular signals for cascade of events.For iron-the signal could be transduced through IRP,removing the inhibition of translation of ferritin.2020年10月

33、2日50The proposed mechanism of PC protection:The small levels of Fe(and Cu?)mobilized during/following the PC serve as signaling species reverting the inhibitory control of ferritin synthesis in heart cells,and are not involved in tissue damage.The high levels of Fe/Cu following prolonged ischemia se

34、rve as catalysts that are involved in the injurious process to the heart.PC yields more apo-ferritin that can scavenge newly mobilezed iron.2020年10月2日51Is Copper Important in PC?Recently published data have indicated important roles for metallothionein(MT)in reperfusion injury and PC.Hearts from tra

35、nsgenic mice that overproduced MT were better protected against ischemia(as indicated by infarct size,hemodynamic function and leakage of proteins),than hearts from non-trangenic animals(Kang,Li&Saari,1999)2020年10月2日52Ischemic-PC of the brain was found to provide protection against edema and neuropa

36、thology,in kainic acid-induced status epilepticus.This protection was dependent on protein synthesis(Emerson et al.,2000).Analysis of MT-1,MT-2 and heme oxygenase-1(HO-1)revealed that the PC had induced a pattern of induction and suppression of these genes,that have led to an adaptive response,preventing the seizure-associated neuropathology.2020年10月2日53演讲完毕，谢谢观看！Thank you for reading!In order to facilitate learning and use,the content of this document can be modified,adjusted and printed at will after downloading.Welcome to download!汇报人：XXX 汇报日期：20XX年10月10日54