血管紧张素Ⅱ对大鼠肝星状细胞收缩及Rho-Rock通路的影响

目的 探讨血管紧张素Ⅱ(AngⅡ)对大鼠肝星状细胞(HSC)ROCk通路的影响机制.方法 采用HSC-T6细胞株,给予AngⅡμmol/L处理,聚硅酮膜法直观检测HSC的收缩性;另予AngⅡ 10 μmol/L处理,免疫印迹法检测肌球蛋白轻链(MLC)磷酸化的表达水平.观察AngⅡ 1型受体(AT-1受体)阻断剂伊贝沙坦和Rho激酶特异性抑制剂Y27632对磷酸化MLC表达水平的影响;逆转录聚合酶链反应检测Rock通路Rock2(Rho kinase 2)mRNA的表达.结果 AngⅡ可诱导磷酸化MLC蛋白水平的变化,并呈时间依赖性,15min达到峰值后逐渐减低.伊贝沙坦和Y27632处理组可抑制AngⅡ诱导的MLC蛋白磷酸化水平.AngⅡ处理组Rock2 mRNA的表达显著增强,伊贝沙坦和Y27632均可抑制Rock2 mRNA的表达.结论 AngⅡ可以通过Rock通路来诱导HSC的收缩.

Effect of angiotensin II on Rho-Rock pathway in rat hepatic stellate cell contraction

OBJECTIVE: To investigate the mechanisms of angiotonin II (AngII)-induced Ca(2+)-independent pathways mediated by Rho kinase in hepatic stellate cells (HSCs). METHODS: HSC-T6 cells were treated with 1 micromol/L of AngII, and the subsequent cell contraction was directly observed with silicone rubber membrane culture method. The cells with 10 micromol/L AngII treatment were examined for myosin light chain (MLC) phosphorylation level using Western blotting, and the effects of irbesartan (a specific inhibitor of AngII 1- receptor) and Y27632 (a Rho kinase inhibitor) on AngII-induced MLC phosphorylation were evaluated. RT-PCR was used to detect the expression of Rock2 in Ca(2+)- independent pathways mediated by Rho kinase. RESULTS: AngII induced HSC contraction and time-dependent MLC phosphorylation changes, which peaked 15 min after the treatment followed by gradual reduction. Irbesartan or Y27632 treatment significantly lowered MLC phosphorylation level in AngII-induced cells (P<0.01). The mRNA expression of Rock2 increased significantly after AngII treatment (P<0.01), but decreased following subsequent irbesartan or Y27632 treatment. CONCLUSION: AngII induces HSC contraction through Ca(2+)-independent pathways mediated by Rho kinase.