【摘要】 目的 :观察钙调神经磷酸酶 (CaN)在血管紧张素Ⅱ (AngⅡ )刺激的大鼠心肌细胞肥大中的作用及其活性调节。方法 :建立AngⅡ诱导的大鼠心肌细胞肥大模型 ,观察CaN抑制剂对AngⅡ刺激的心肌细胞 [3H]-亮氨酸掺入的影响 ,以及各种因素对心肌细胞CaN酶活性的影响。结果 :10、10 0、10 0 0nmol·L-1的AngⅡ作用 12h分别使心肌细胞的CaN活性增加了 13%、5 7% (P <0 0 5 )、2 2 8% (P <0 0 1)。AngⅡ (10nmol·L-1)刺激心肌细胞 2h内 ,CaN活性与对照组无明显差异 (P <0 0 5 ) ;AngⅡ刺激心肌细胞 12h以上 ,CaN活性才明显增高 (P <0 0 5 )。Losartan(5 0 μmol·L-1)、H7(5 0 μmol·L-1)及Fura - 2 /AM(4 μmol·L-1)可明显抑制AngⅡ刺激的心肌细胞CaN活性 ;而PD980 5 9(5 0 μmol·L-1)对AngⅡ刺激的心肌细胞CaN活性无明显影响。AngⅡ (10 -7mol/L)刺激的大鼠心肌细胞 [3H]-亮氨酸掺入明显高于对照组 (P <0 0 1) ,而CaN特异性抑制剂 -环孢素A(0 5～ 5 μg/mL)可以明显抑制AngⅡ刺激的心肌细胞 [3H]-亮氨酸掺入。结论 :依赖Ca2 +/CaM活化的CaN可能在AngⅡ刺激的心肌细胞肥大中起重要作用 ;CaN的活化可能有赖于胞内Ca2 +水平的持续升高 ,另外 ,CaN的活性还可能受到蛋白激酶C等信号分子的磷酸化调节更多还原

【Abstract】 AIM: To study the role and regulation of calcineurin(CaN) in angiotensin II(AngⅡ)-stimulated cardiacmyocyte hypertrophy of rats. METHODS: Using AngⅡ to induce the cultured cardiac myocyte hypertrophy of rats, and investigating the effect of CaN inhibitor on [ 3H]-leucine incorporation of AngⅡ-stimulated cardiomyocytes and the regulation of various factors on CaN activity in cardiomyocytes.RESULTS: AngⅡ can stimulate the CaN activity in cultured neonatal rat cardiomyocytes in a dose- and time-dependent manner. In cardiac myocytes incubated with 10, 100, 1000 nmol·L -1 of AngⅡ for 12h, the CaN activities increased respectively by 13%,57%( P<0.05 ) and 228%( P< 0.01) compared with that in non-stimulated cardiomyocytes. The CaN activities in AngⅡ-stimulated cardiomyocytes were significantly inhibited by losartan(50 μmol·L -1 ), H 7(50 μmol·L -1 )and Fura-2/AM(4 μmol·L -1 ),while no effect was observed with PD98059(50 μmol·L -1 ). The [ 3H]-leucine incorporation in AngⅡ-stimulated cardiomyocytes increased by 46%( P< 0.01) compared with that in control group, which was dramatically inhibited by cyclosporin A(0.5～5 μg/mL). CONCLUSIONS: Calcineurin, a Ca 2+ /calmodulin-dependent protein phosphatase, may play an important role in AngⅡ-induced cardiac myocyte hypertrophy. The activation of CaN may dependent on the sustained increases of [Ca 2+ ]i and be regulated by some protein kinases (such as PKC,etc.).更多还原