Role of cAMP-PKA signal transduction pathway in the ischemic preconditioning-induced attenuation of ischemia-reperfusion injury In isolated rat hearts / 中华麻醉学杂志

ABSTRACT

Objective To investigate the role of cAMP-PKA signal transduction pathway in the ischemie pleeonditioning-induced attenuation of ischemia.1eperfusion(ITR)injury in isohted rat hearts.Methods Fifty healthy adult SD rats weighing 300-350 g were anesthetized with intraperitoneal(IP)pentobarbital 50 meg/kg.Their he.arts were excised and perfused in a Langendorff apparatus with 37℃ oxygenated(95%O2-5%CO2)modified K-H solution at a constant pressure of 70 cm H2O,and randomly divided into 5 groups(n=10 each)group Ⅰ I/R;group Ⅱ ischemic preconditioning(IPC);groupⅢH89(PKA inhibitor);group Ⅳ PDTC(NF-κB inhibitor)and group Ⅴ db-cAMP.The experiment started after 10 min stabilization.The isolated hearts were tinct perfuzed for 30 min.followed by 60 min ischemia and 30 min leperfusion in group I/R(Ⅰ).Group IPC(Ⅱ)w88 subjected to 3 episodes of 5 min ischemia at 5 min intervals before I/R.Group Ⅲ and Ⅳ received 5 min perfnsion withH89 10 μmol/L and PDTC 100 μmol/L 3 times at 5 min intervals respectively before I/R.Group Ⅴ was peffnsed with db-cAMP 200 μmol/L for 30 min before I/R.Left ventricular developed pressure(LVDP)and ± dp/dtu were measured at stabilization period and 10, 20, 30 rain of reperfusion. Coronary flow (CF) was measured at stabilization period and 30 min of reperfusion and activities of LDH and creafinc kinase (CK) in the coronary effluent were determined. The myocardial specimens were obtained at 30 rain of reperfusion for determination of NF-κB-DNA binding activity (by EMSA) and expression of TNF-κ mBNA (by RT-PCR ) and p-CBEB (Ser133) (by Western blot). Results Compared with 1/R group, NF-κB-DNA binding activity and TNF-α mRNA expression were significandy decreased, ± dp/dt and CF were significandy increased, CK and LHD activities in the coronary effluent were significantly decreased in group IPC and db-cAMP (group Ⅱ , Ⅴ ) and p-CREB (Ser133) expression was significantly increased in group IPC, PDTC and db-cAMP (group Ⅱ , Ⅳ,Ⅴ ). Compared with IPC group, NF-κB-DNA binding activity and TNF-α mBNA expression were significantly increased, ± dp/dtmax, LVDP and CF were significantly decreased, CK and LDH activities were significantly increased in group H89 and PDTC (group Ⅲ, Ⅳ ) and p-CREB (Ser133) expression was significantly decreased in group H89(group Ⅲ ). Conclusion lschemic preconditioning can attenuate I/R injury in isolated hearts by inhibition of NF-κB-DNA binding activity via cAMP-PKA signal transduction pathway which reduces gene transcription of inflammatory cytokine.