丝裂素活化蛋白激酶参与心肌缺氧预处理的延迟保护作用

Mitogen-activated protein kinase involved in the delayed protection after hypoxic preconditioning in cultured cardiomyocytes

目的 探讨丝裂素活化蛋白激酶 (mitogen- activated protein kinase,MAPK)在心肌缺氧预处理延迟保护中的作用。方法 在培养乳鼠心肌细胞缺氧预处理的模型上 ,检测预处理后即刻、1h、6 h和 12 h的 MAPK活性变化 ,观察细胞缺氧 /复氧损伤后、延迟预处理后及蛋白激酶 C(PKC)抑制剂 chelerythrine(Ch)干预后的细胞存活率、L DH的释放、MDA含量和 SOD活性。结果 MAPK活性在预处理后即刻明显增加 (P<0 .0 1) ,在 6 h后降至或接近对照水平。与未预处理组心肌细胞缺氧 /复氧损伤相比较 ,预处理后 2 4 h心肌细胞存活率增高 [(5 8.6 4± 5 .5 3) %vs (44 .2 9± 4 .2 7) % ,P<0 .0 1],L DH[(5 9.5 0± 11.0 8) U/ L vs(83.17± 13.6 9) U/ L,P<0 .0 1]和 MDA含量[(2 .33± 0 .4 9) nmol/ L vs(3.2 9± 0 .2 6 ) nmol/ L,P<0 .0 1]均降低 ,SOD活性增加 [(2 1.5 3± 3.6 3) n U/ m l vs(12 .86± 2 .6 8) n U/ ml,P<0 .0 1]。PKC抑制剂 chelerythrine可消除预处理的延迟保护作用。结论 预处理 2 4 h心肌细胞对再次缺氧 /复氧有保护作用 ,PKC。

Objective To detect mitogen-activated protein kinase(MAPK) involved in the delayed protection (DP) of preconditioning (PC). Methods MAPK activities in cultured cardiomyocytes were assayed at the 0h,1h,6h,12h after PC. The cell viability, LDH release, the content of MDA and activity of SOD were measured with or without DP and with the intervention of chelerythrine, the inhibitor of PKC. Results MAPK activities were increased significantly immediately after PC (P<0.01) and decreased to control level at 6h after PC (P>0.05) compared with the normal group. Compared with the cardiomyocytes without DP, the cell viability [(58.64±5.53)% vs (44.29±4.27)%,P<0.01] was greatly increased, the LDH release [(59.50±11.08) U/L vs (83.17±13.69)U/L,P<0.01] and the MDA contents [(2.33±0.49) nmol/L vs (3.29±0.26)nmol/L,P<0.01], were decreased, the SOD activites [(21.53±3.63) nU/ml vs (12.86±2.68)nU/ml,P<0.01] were increased significantly in delayed protection group. The inhibitor of PKC completely removed all delayed protection at 24h after PC. Conclusion The cardiomyocytes at 24 h after PC are offered more capacity to tolerate the hypoxia/reoxygenation(H/R) damage, and MAPK involved in the delayed protection.