心肌缺血预处理优选课件

1、EARLY SIGNALING PATHWAY IN HEART PROTECTION BY ISCHEMIC PRECONDITIONING2020/10/181EARLY SIGNALING PATHWAY IN HEAIschemic 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

2、 ischemia and reperfusion.2020/10/182Ischemic preconditioning (PC) An analogous phenomenon of cardiac protection against reperfusion injury by pre-administration of a drug is called drug-induced PC. We have developed a family of drugs that can do it. 2020/10/183An analogous phenomenon of carIschemia

3、R1R2Stabilization10 minReperfusion20 minPc 1 Pc 2 Pc 3R3The System: Isolated rat heartThe procedure : Three episodes of 2 globalischemia separated by 3 reperfusion PC2020/10/184IschemiaR1R2StabilizationReperTwo windows of protection by ischemic PC have been identified: 1 3 hours following PC, and 24

4、 hour following PC. We work with the isolated rat heart, and will focus on the first window.2020/10/185Two windows of protection by iCardiac Function without and with PC has been studied. Below the following parameters are presented:DP = PSP - EDP+dP/dt EDPother parameters not shown2020/10/186Cardia

5、c Function without and wDeveloped Pressure (DP) (% of pre-ischemic value) Versus Ischemic Time Preconditioning (PC)2020/10/187Developed Pressure (DP) (% of +dP/dt (%) Versus Ischemic Time Preconditioning (CPC)2020/10/188+dP/dt (%) Versus Ischemic TimEDP (mmHg) Versus Ischemic Time Preconditioning (C

6、PC)2020/10/189EDP (mmHg) Versus Ischemic TimBIOCHEMISTRYBIOCHEMISTRY Biochemical parameters of the heart tissue: a similar protection was observed for ATP, energy charge, ascorbate and other parameters. in the coronary flow: leakage into the CF of cellular metabolites:2020/10/1810BIOCHEMISTRYBIOCHEM

7、ISTRY2020/1HPLC Analysis of the First 10-CFFsFollowing 35 Global Ischemia PC010203040506070Control: ischemia of 35- no PCPreconditioning followed by 35 ischemiaSASPUAInoAA2020/10/1811HPLC Analysis of the First 10-Currently Proposed Mechanisms of Protection by PCThe detailed understanding of the mech

8、anism 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;2020/10/1812Currently Proposed Mechanisms increase in antioxidants activity;synthesis of heat-shock p

9、roteins, 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 PC2020/10/1813increase in antioxidants activROS - Reactive Oxygen Species - in reperfusi

10、on 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.2020/10/1814ROS - Reactive Oxygen Species Two lines of evidence support this idea:Inclu

11、sion of iron chelators in 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.2020/10/1815Two lines of evidence support McCords Scheme for Myocardial Damage Fol

12、lowing Ischemia and Reperfusion reoxygenationIschemia2020/10/1816McCords Scheme for MyocardialMcCord scheme Ischemia reoxygenationATP AMPAdenosine InosineHypoxanthine2020/10/1817McCord scheme Ischemia reoxMcCord scheme Ischemia reoxygenationATP AMPAdenosine InosineHypoxanthineXanthinedehydrogenaseXa

13、nthineoxidase2020/10/1818McCord scheme Ischemia reoxMcCord scheme Ischemia reoxygenationATP AMPAdenosine InosineHypoxanthineXanthinedehydrogenaseXanthineoxidaseCa2+ Protease2020/10/1819McCord scheme Ischemia reoxMcCord scheme Ischemia reoxygenationATP AMPAdenosine InosineHypoxanthineXanthinedehydrog

14、enaseXanthineoxidaseO2Ca2+ ProteaseO22020/10/1820McCord scheme Ischemia reoxMcCord scheme-modified Ischemia reoxygenationATP AMPAdenosine InosineHypoxanthineXanthinedehydrogenaseXanthineoxidaseO2Ca2+ ProteaseO2 OH2020/10/1821McCord scheme-modified IschemMcCord scheme -modified Ischemia reoxygenation

15、ATP AMPAdenosine InosineHypoxanthineXanthinedehydrogenaseXanthineoxidaseO2Ca2+ ProteaseO2 OHCu/Fe2020/10/1822McCord scheme -modified IscheFe(II) + H2O2 Fe(III) + OH- + OHFenton Reaction2020/10/1823Fe(II) + H2O2 Fe(III) + OHHaber Weiss Reactionor Superoxide-Driven Fenton ReactionO2 + Fe(III) O2 + Fe(

16、II) (1)Fe(II) + H2O2 Fe(III) + OH- + OH(2) O2 + H2O2 OH + OH- + O2 (3)-2020/10/1824Haber Weiss Reactionor SuperFe 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

17、, mobility and reactivity).2020/10/1825Fe and Cu2020/10/1825Cardiac 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 injury2020/1

18、0/18262020/10/1826MOBILIZATION OF Fe/Cu into CORONARY FLOW FRACTIONSCFF#1 versus TOTAL Fe/Cu02040608010012014018 3560CFF #9876543210Fe (ng/ml)2020/10/1827MOBILIZATION OF Fe/Cu into CORTOTAL Fe levels in the CFFs #1 Versus Ischemic Time Preconditioning70605040302010020406080100120140ControlPCDuration

19、 of IschemiaFe (ng/ml)2020/10/1828TOTAL Fe levels in the CFFs #1TOTAL Cu levels in the CFFs #1 Versus Ischemic Time Preconditioning7060504030201001020304050ControlPCDuration of IschemiaCu (ng/ml)2020/10/1829TOTAL Cu levels in the CFFs #12020/10/18302020/10/1830Isolated Rat Heart (Langendorff) R1R2Is

20、chTime:10 2 3 2 3 2 3 18 - 60 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 2020/10/1831Isolated Rat Heart (LangendorfIron in the CFFs following Global Ischemia without PC02040608010012014018 3560CFF #9876543210Fe (ng/ml)2020/10/1832Iron in the CF

21、Fs following GloIron in CFFs FollowingPC and Global Ischemia03570105140CFF #0 1 2 1 2 1 2 pc1 pc2 pc31 2 3 4 5 6 7 8 9 102020/10/1833Iron in CFFs FollowingPC andCopper in the CFFs following Global Ischemia 109876543210010203040CFF#18 3560Cu(ng/ml)2020/10/1834Copper in the CFFs following Copper in Th

22、e 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)2020/10/1835Copper in The CFFs Following Ischemia 18Ischemia 35Ischemia 6001-11-22-12-23-13-24020100300408012016012345678910123456789100408012016001-11-22-12-23-13-2040801201601

23、234567891040201003012345678910402010030Cu (ng/ml)Fe (ng/ml)2020/10/1836Ischemia 18Ischemia 35IschemTOTAL Fe/Cu versus LAMP (LIP)Is it the total Fe/Cu that plays a role in mediation of injury?“LAMP” - the LAbile transitionMetals Pool is the active fraction, and is important! The over-estimated values

24、 in the literatureHow can we quantitate LAMP?2020/10/18372020/10/1837CFF-LAMP Mediated Conversion of Salicylate to 2,5-DHBA7060504030201001020304050ControlPCDuration of Ischemia2,5-DHBA (ng/ml)2020/10/1838CFF-LAMP Mediated Conversion oCFF-LAMP Mediated Conversion of Salicylate to 2,3-DHBA 7060504030

25、2010-551525354555ControlPCDuration of Ischemia2,3-DHBA (ng/ml)2020/10/1839CFF-LAMP Mediated Conversion oThree levels of mobilized metal ions:PC phaseprolonged ischemia following PCprolonged ischemia2020/10/1840Three levels of mobilized 2020Ferritin Levels in Heart Tissue and in Coronary Flow (CF) fo

26、llowing 35 ischemia HEART TISSUE Total Ft inFt/ProteinFe/Protein CF (mg/mg) (mg/mg) (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+0.052020/10/1841Ferritin Levels in Heart T

27、issuIron Level in Heart Tissue Ferritin (mg/mg)Experimental GroupFe in Ferritin (mg/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+0.012020/10/1842Iron Level in Heart Tissue FerThree levels of mobilization of iron: high levels are as

28、sociated with tissue injury.The PC phase: low levels of mobilized iron (and copper) and no damage.Removal of the inhibitory control of protein synthesis through the conversion of IRP to Aconitase.2020/10/1843Three levels of mobilization o FerritinFerritin is an intracellular iron binding protein, ab

29、le to store about 4,000-4,500 iron atoms per molecule. Under normal conditions the amount of iron in heart Ferritin is about 1,500-2,500 iron atoms. 2020/10/1844 FerritinFerritin is an intracFerritinSullivan (1981) and Salonen et al. (1992) reported an association between the increase of iron stores

30、 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 Enbergs et al (1998), on the other hand, did not find such a correlation between ferritin levels and myocardial infarction.Recent publicatio

31、ns (1997 - 2000) tend to support the claim that ferritin is a marked risk factor for AMI.2020/10/1845FerritinSullivan (1981) and SaDoes Ferritin Synthesis take place during or following PC ?Is protein synthesis required for PC? Does it involve transcriptional or translational control?2020/10/1846Doe

32、s Ferritin Synthesis take pFerritin 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. (1998) showed that ischemia-reperfusion and oxidative stress lead to

33、 inhibition of IRP activity followed by activation of ferritin synthesis.2020/10/1847Ferritin synthesisWhite and MuSeveral studies have indicated that protein synthesis is required for PC. The PC effect was abolished only with cycloheximide, but not with actinomycin D, indicating that PC is regulate

34、d 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 episode was applied (Thornton e

35、t al., 1990). 2020/10/1848Several studies have indicated 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. 2020/10/1

36、849 Our preliminary results indicSignaling 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

37、inhibition of translation of ferritin.2020/10/1850Signaling with “LAMP” in PCDurThe 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 F