川芎嗪对血管紧张素Ⅱ诱导心肌细胞肥大的影响及其机制

Effects of Tetramethylpyrazine on Ang Ⅱ-induced Cardiomyocyte Hypertrophy and the Underlying Mechanisms

摘要:

目的: 探讨川芎嗪(TMP)对血管紧张素Ⅱ(Ang Ⅱ)所诱导心肌细胞肥大的抑制作用及其机制。方法: 利用Ang Ⅱ(0.1 μmol·L^-1)刺激新生大鼠心肌细胞建立肥大细胞模型。培养心肌细胞随机分为6组:对照组,Ang Ⅱ(0.1 μmol·L^-1)组,低剂量TMP(0.01 mmol·L^-1)组,中剂量TMP(0.1 mmol·L^-1)组,高剂量TMP(1 mmol·L^-1)组,吡咯烷二硫化氨基甲酸酯(PDTC,100 μmol·L^-1)组。在给药处理24 h后,收集各组心肌细胞,检测心肌细胞总蛋白含量、β-肌球蛋白重链(β-MHC)mRNA表达量和核因子-κB(NF-κB)蛋白表达量。结果: Ang Ⅱ刺激导致培养心肌细胞的总蛋白含量[Ang Ⅱ组(296.7±27.6)mg·L^-1,对照组(184.3±11.6)mg·L^-1,P<0.05]、β-MHC mRNA表达量(Ang Ⅱ组0.936±0.059,对照组0.496±0.030;P<0.05)明显增加,这证实心肌肥大的发生;TMP以剂量依赖的方式抑制Ang Ⅱ诱导的心肌细胞肥大。同时TMP 1 mmol·L^-1降低Ang Ⅱ诱导的肥大心肌细胞中磷酸化NF-κB(Ang Ⅱ组0.861±0.065,TMP组0.655±0.052,P<0.05)和I-κB蛋白的表达量(Ang Ⅱ 组0.785±0.042,TMP组0.525±0.045,P<0.05)。在应用Ang Ⅱ刺激心肌细胞同时,给予NF-κB抑制剂PDTC也能抑制Ang Ⅱ诱导的心肌细胞肥大。结论: 川芎嗪通过抑制心肌细胞内NF-κB途径,而抑制Ang Ⅱ诱导的心肌细胞肥大。川芎嗪的这些作用构成了它对心脏疾病具有保护作用的机制之一。

Abstract:

Objective: To investigate the inhibitory effects of tetramethylpyrazinee(TMP) on angiotensin Ⅱ (Ang Ⅱ)-induced cardiomyocyte hypertrophy and the underlying mechanisms. Method: Ang Ⅱ-induced cardiomyocyte hypertrophy model was established in isolated neonatal rat ventricular myocytes. The cells were then randomly divided into 6 groups:control group, Ang Ⅱ (0.1 μmol·L^-1) group, low-dose TMP (0.01 mmol·L^-1) group, middle-dose TMP (0.1 mmol·L^-1) group, high-dose TMP (1 mmol·L^-1) group, pyrolidine dithiocarbamate(PDTC, a NF-κB inhibitor, 100 μmol·L^-1) group. After 24 h treatment, cardiomyocytes were harvested to measure total protein content by Lowry's method, β-myosin heavy chain (β-MHC) mRNA expression by Real-time PCR, and NF-κB content by Western blotting. Result: Ang Ⅱ induced cardiomyocyte hypertrophy characterized by increased total protein content [Ang Ⅱ groupg(296.7±27.6) mg·L^-1;control group(184.3±11.6) mg L^-1,P<0.05]·L^-1;control group(184.3±11.6) mg·L^-1,P<0.05] and enhanced β-MHC mRNA expression (Ang Ⅱ group 0.936±0.059;control group 0.496±0.030,P<0.05), while TMP significantly inhibited Ang Ⅱ-induced hypertrophic growth in a dose-dependent manner. Meanwhile, TMP (1 mmol·L^-1) also attenuated Ang Ⅱ-induced increase in phosphorylated NF-κB (Ang Ⅱ group 0.861±0.065;TMP group 0.655±0.052,P<0.05) and I-κB protein content (Ang Ⅱ group 0.785±0.042;TMP group 0.525±0.045,P<0.05) in cardiomyocytes. Furthermore, inhibition of NF-κB by the specific inhibitor PDTC markedly suppressed Ang Ⅱ-induced hypertrophic responses. Conclusion: Our findings suggested that TMP inhibits Ang Ⅱ-induced cardiomyocyte hypertrophy through suppression of NF-κB pathway, which might contribute to the protective role of TMP in cardiac diseases.