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目的探讨糖尿病大鼠心肌缺血预处理(IPC)后环磷酸腺苷(cAMP)及环磷酸腺苷依赖蛋白激酶(PKA)表达的变化。方法选取糖尿病与非糖尿病SD大鼠各30只,分为3组(n=10):假手术(Sham)组,缺血再灌注(I/R)组及IPC组。比较各组血清肌酸激酶(CK)、肌酸激酶同工酶(CK-MB)、乳酸脱氢酶(LDH)、心肌梗死面积(MI)及心肌cAMP、PKA含量的变化。电镜标本观察心肌线粒体。结果非糖尿病大鼠中,IPC组与I/R组比较,CK减少[(2428.32±170.19)vs(6324.06±356.26)U/L,P<0.05],LDH减少[(1698.98±129.65)vs(4660.15±115.34)U/L,P<0.05],CK-MB减少[(1450.43±23.56)vs(3280.90±71.33)U/L,P<0.05],MI减少[(5.63±9.32)%vs(17.75±7.36)%,P<0.05]。糖尿病大鼠中,IPC组与I/R组比较,CK、LDH、CK-MB、MI未见明显缩小[(5962.63±145.22)vs(6012.13±124.08)U/L,(5998.44±123.40)vs(6023.54±89.01)U/L,(4011.13±81.09)vs(4380.71±76.21)U/L,(13.54±2.39)%vs(15.25±4.33)%,P>0.05]。非糖尿病大鼠中,IPC组与I/R组比较,cAMP增加[(0.61±0.07)vs(0.32±0.06)pmol/g,P<0.05],PKA含量增加[(17.05±1.75)vs(12.68±1.13)pmol/(mg·min),P<0.05],糖尿病大鼠IPC组cAMP、PKA含量无明显增加[(0.35±0.04)vs(0.37±0.08)pmol/g,(12.14±2.15)vs(11.79±1.16)pmol/(mg·min),P>0.05]。非糖尿病大鼠IPC组线粒体的损伤减轻,而糖尿病大鼠IPC组线粒体损伤未见减轻。结论非糖尿病大鼠IPC可保护心肌。糖尿病抑制IPC的心肌保护作用,其机制可能与糖尿病大鼠心肌cAMP信号系统表达受抑制有关。
Objective To investigate the changes of cAMP and cAMP in diabetic rats after myocardial ischemic preconditioning (IPC). Methods Thirty diabetic and non-diabetic SD rats were divided into three groups (n = 10): sham group, ischemia / reperfusion (I / R) group and IPC group. The changes of serum creatine kinase (CK), creatine kinase (CK-MB), lactate dehydrogenase (LDH), myocardial infarct size (MI) Electron microscope observation of myocardial mitochondria. Results Compared with the I / R group, the CK decreased (2428.32 ± 170.19 vs 6324.06 ± 356.26 U / L, P <0.05), and the LDH decreased in the non-diabetic rats [(1698.98 ± 129.65) vs (4660.15 (P <0.05)], and the decrease of CK was (5.63 ± 9.32)% vs (17.75 ± 0.45) U / L, P < 7.36)%, P <0.05]. Compared with I / R group, there was no significant decrease of CK, LDH, CK-MB and MI in diabetic rats [(5962.63 ± 145.22) vs (6012.13 ± 124.08) U / L, (5998.44 ± 123.40 vs 6023.54 ± 89.01 U / L, (4011.13 ± 81.09) vs (4380.71 ± 76.21) U / L, (13.54 ± 2.39)% vs (15.25 ± 4.33)%, P> 0.05. Compared with I / R group, the increase of PKA in group of non-diabetic rats [(0.61 ± 0.07) vs (0.32 ± 0.06) pmol / g, P <0.05] (0.35 ± 0.04 vs 0.37 ± 0.08) pmol / g, (12.14 ± 2.15) vs (P <0.05), P <0.05) (11.79 ± 1.16) pmol / (mg · min), P> 0.05]. The damage of mitochondria in IPC group was alleviated in non-diabetic rats, while the mitochondrial damage in diabetic rats was not alleviated. Conclusion Non-diabetic rats can protect myocardium. Diabetes mellitus can inhibit the cardioprotection of IPC, which may be related to the inhibition of cAMP signaling system in diabetic rats.