1. Role of Adenosine Receptor in Ischemic Preconditioning

2. Basic Knowledge 1.what is ischemic preconditioning (IPC)? A phenomenon by which a brief episodes of myocardial ischemia increases the ability of the heart to tolerate a subseqent prolonged period of ischemic injury. 2. Early phase (‘classical’conditioning ) and delayed phase (‘second window’of protection) Early phase appears immediately; delayed phase appears at 24,48,72 hours following brief periods of preconditioning ischemia.

3. 3.Triggers of ischemic preconditioning 1)Receptor dependent triggers A. Adenosine receptors B. Opioid receptors 2)Receptor independent triggers A.Nitric oxide B. Free radicals

4. Subtypes and Distributing of Adenosine receptors

5. A1 adenosine receptor (A1AR) A1AR is found in the myocytes and in the vascular smooth muscle. A2 adenosine receptor (A2AR) A2AR including A2A and A2B,can be found in the endothelium and the vascular smooth muscle. A3 adenosine receptor (A3AR) Locate in the plasmatic membrane of the myocytes.

6. Structures of Adenosine Receptors

7. Fig.1.Sructures of adenosine receptor

8. Adenosine receptors are G- protein coupled receptors

9. Fig.2. Adenosine receptor subtypes and their coupled G-proteins.

10. A1 Adenosine Receptor Participates in Early Phase of Ischemic Preconditioning

11. Fig.3.Values of left ventricular developed pressure (LVDP), in the control group,the group treated with adenosine, and the group where adenosine and DPCPX (A1 blocker) were administered.Note that adenosine attenuated the systolic alterations of post ischemic dysfunction. This effect was abolished with the administation of DPCPX.*P<0.05 vs. control.

12. Fig.4.Size of the infarct expressed as percentage of the area of the left ventricle in the control group, the group treated with adenosine,and the group where adenosine plus DDCPX(A1 blocker) was administered.*p<0.05 vs control.

13. A3 Adenosine Receptor Participates in early preconditioning

14. Fig.5.The effect of 1microM MRS-1191 (adenosine A3 receptor antagonist ) upon protection conferred by 2-Cl-IB-MECA at reperfusion.

15. Fig.6. Protective effect of activation of adenosine receptor A1 and A3.

16. Late Preconditioning Elicited by Activation of Adenosine A1 Receptor

17. Fig.7. Principal experimental evidence for participation of adenosine as a trigger of delayed preconditioning and for delayed myocardial protection induced by selective activation of adenosine receptor subtypes

18. Fig.8. Cellular protection against SI in A1AR- tgm compared with wt.(Wt:wild-type-mice;SMT, an iNOS inhibitor; Glb: a KATP channel blocker; 5-HD:a mitochondrial KATP channel blocker).

19. Late Preconditioning Elicited by Activation of Adenosine A3 Receptor

20. Fig.9.Effect of A3AR stimulation on attenuation in ischemia/reperfusion jury

21. Possible Pathways Mediated by Adenosine Receptors in Ischemic Preconditioning

22. 1.Molecules Invovled in Ischemic Preconditioning ATP-sensitive K channel PKC and tyrosine kinases p38 MAP kinase Heat shock protein (HSP27) Nuclear factor-κB and AP-1 Superoxide dismutase Inducible nitric oxide symthase

23. Fig.12. Abrogation of protection provided by adenosine

24. 1.Molecules Invovled in Ischemic Preconditioning ATP-sensitive K channel PKC and tyrosine kinases p38 MAP kinase Heat shock protein (HSP27) Nuclear factor-κB and AP-1 Superoxide dismutase Inducible nitric oxide symthase

25. Fig.13. Effect of rottlerin (PKC-δ specific inhibitor) on infarct size confered by CCPA.

26. C Fig.14. Western blot analysis of PKC-δ (A), PKC-ε (B) and iNOS (C).

27. 1.Molecules Invovled in Ischemic Preconditioning ATP-sensitive K channel PKC and tyrosine kinases p38 MAP kinase Heat shock protein (HSP27) Nuclear factor-κB and AP-1 Superoxide dismutase Inducible nitric oxide symthase

28. 1.Molecules Invovled in Ischemic Preconditioning ATP-sensitive K channel PKC and tyrosine kinases p38 MAP kinase Heat shock protein (HSP27) Nuclear factor-κB and AP-1 Superoxide dismutase Inducible nitric oxide symthase

29. 1.Molecules Invovled in Ischemic Preconditioning ATP-sensitive K channel PKC and tyrosine kinases p38 MAP kinase Heat shock protein (HSP27) Nuclear factor-κB and AP-1 Superoxide dismutase Inducible nitric oxide symthase

30. Fig.10. Nuclear Factor κB in A3AR- induced myocardial protection

31. Fig.15. Nuclear factor-κB expression after treatment with IB-MECA

32. 1.Molecules Invovled in Ischemic Preconditioning ATP-sensitive K channel PKC and tyrosine kinases p38 MAP kinase Heat shock protein (HSP27) Nuclear factor-κB and AP-1 Superoxide dismutase Inducible nitric oxide symthase

33. 1.Molecules Invovled in Ischemic Preconditioning ATP-sensitive K channel PKC and tyrosine kinases p38 MAP kinase Heat shock protein (HSP27) Nuclear factor-κB and AP-1 Superoxide dismutase Inducible nitric oxide symthase

34. Fig.11.Role of NO in A3AR-induced protection.

35. Fig.16. RT-PCR showing iNOS and β-actin transcription by IB-MECA.

36. 2.Possible pathways Fig.17. Primary and secondary pathways in early ischemic preconditioning

37. Fig.18.Outline of the principal stages leading to cellular adaptation in delayed preconditioning.Several diffusible mediators including adenosine,contribute critically to the trigger phase that initiates the adaptive response.

38. Fig.19. Hypothetical pathways by which adenosine receptor activation might lead to the delayed protection

39. Thank you!