左卡尼汀对过氧化氢诱导的心肌细胞凋亡的抑制作用(英文)

目的探讨左旋尼汀对心肌细胞凋亡的抑制作用及其可能的作用机制。方法采用培养的新生乳大鼠心肌细胞制备H2O2200μmol.L-1氧化损伤模型。实验分为正常对照组、H2O2200μmol.L-1模型组、左卡尼汀(0.3,0.6及1.2 mmol.L-1)组、左卡尼汀1.2 mmol.L-1+H2O2200μmol.L-1组。左卡尼汀0.3,0.6和1.2 mmol.L-1作用1 h后加入H2O2200μmol.L-1培养12 h,MTT法测定心肌细胞存活率,流式细胞仪测定心肌细胞的凋亡率,Western印迹法测定胱天蛋白酶3表达;用试剂盒方法检测过氧化物歧化酶(SOD)活性和丙二醛(MDA)水平。左卡尼汀1.2 mmol.L-1作用5 min后加入H2O2200μmol.L-1,采用Till阳离子测定系统监测5 min的心肌细胞Ca2+]i瞬间变化。结果 H2O2200μmol.L-1作用于心肌细胞12 h能引起心肌细胞凋亡。左卡尼汀0.3,0.6和1.2 mmol.L-1能够不同程度的逆转由H2O2所致的损伤,使SOD活性明显增加,MDA水平明显降低(P<0.01)。左卡尼汀1.2 mmol.L-1作用最强,能够明显降低心肌细胞胱天蛋白酶3表达(P<0.01),明显降低H2O2引起的Ca2+]i瞬间变化升高(P<0.01),但对于H2O2引起无钙血清培养的心肌细胞静息钙升高无影响。结论左卡尼汀能够抑制由H2O2引起的心肌细胞凋亡,该抑制作用可能与其保护细胞膜和减轻钙通道的损害、纠正Ca2+]i瞬变失调及其抗氧化作用有关。

Inhibitory effect of L-carnitine on cardiomyocyte apoptosis induced by hydrogen peroxide

OBJECTIVE To investigate the effect of L-carnitine on H₂O₂-induced apoptosis in cultured neonatal rat cardiomyocytes and its possible mechanisms. METHODS H₂O₂ 200 μmol·L^-1 was used to set up an oxidative stress induced injury model in neonatal rat cardiomyocytes. There were normal control, H₂O₂ 200 μmol·L^-1 model, L-carnitine (0.3, 0.6 and 1.2 mmol·L^-1), L-carnitine (1.2 mmol·L^-1)+H₂O₂ (200 μmol·L^-1) groups in the experiment. The cells were pretreated with L-carnitine 0.3, 0.6 and 1.2 mmol·L^-1 for 1 h before H₂O₂ 200 μmol·L^-1 was added for 12 h. Cell viability was measured by MTT assay and apoptosis was determined by flow cytometry. The expression of caspase 3 was determined by Western blotting. Superoxide dismutase (SOD) and malondialdehyde(MDA) were measured according to the instructions of commercial kits. L-Carnitine 1.2 mmol·L^-1 was added 5 min prior to H₂O₂ 200 μmol·L^-1. H₂O₂ was perfused for 5 min to measure Ca²⁺]_i transient by Till image system by cell loading Fura-2/AM. RESULTS Application of H₂O₂ 200 μmol·L^-1 to myocytes for 12 h could cause cardiomyocyte apoptosis. L-Carnitine 0.3, 0.6 and 1.2 mmol·L^-1 significantly reversed the lesion of primary cultured cardiomyocytes treated with H₂O₂ 200 μmol·L^-1, increased SOD activity(P<0.01), and decreased MDA content(P<0.01). L-Carnitine 1.2 mmol·L^-1 was the most powerful in that it decreased caspase 3 expression(P<0.01) and the adverse effect of H₂O₂ on the Ca²⁺]_i transient was abolished by L-carnitine pretreatment. L-Carnitine had no effect on the elevation of the resting Ca²⁺]_i evoked by H₂O₂ in Ca²⁺-free medium. CONCLUSION L-Carnitine can produce an inhibitory effect on cardiomyocyte apoptosis induced by H₂O₂, which may be mediated by the protective effect on the cell membrane and the damage to voltage-dependent Ca²⁺ channel as well as its inhibition of lipid peroxidation.