【摘要】 目的探讨肾上腺髓质素（ADM）对血管紧张素Ⅱ（AngⅡ）诱导的血管外膜成纤维细胞胶原生成的影响及机制。方法体外培养大鼠主动脉外膜成纤维细胞,通过放射免疫法测定培养上清中 ADM 含量,采用酶联免疫吸附法（ELISA）测定培养上清中Ⅰ、Ⅲ型胶原蛋白含量,用逆转录-聚合酶链反应（RT-PCR）及 Western 印迹法检测转化生长因子β1（TGFβ1）和基质金属蛋白酶-2（MMP-2）mRNA 及蛋白的表达。结果 AngⅡ呈剂量依赖性地刺激血管外膜成纤维细胞分泌 ADM,在 AngⅡ(10^-6mol/L)刺激前30 min 加入氯沙坦或（和）PD123319,氯沙坦(10^-5mol/L)可明显降低AngⅡ刺激的 ADM 分泌,其抑制率为45%（P<0.01）,而 PD123319（10 mmol/L）作用后抑制率仅为3%（P>0.05）,氯沙坦+PD123319组与单独氯沙坦组相比差异无统计学意义（P>0.05）;AngⅡ显著增加培养上清中Ⅰ、Ⅲ型胶原蛋白含量,ADM 呈剂量依赖地抑制 AngⅡ上述作用,其中 ADM(10^-8mol/L)组中Ⅰ、Ⅲ型胶原合成分别抑制了30%和31%（P<0.01）,ADM(10^-7mol/L)组则分别抑制了43%和42%（P<0.01）。ADM 受体拮抗剂 ADM_22-52可增强 AngⅡ上述作用,Ⅰ、Ⅲ型胶原合成分别增加了38%和43%（P<0.01）;ADM 呈剂量依赖性抑制 AngⅡ刺激的 TGFβ1 mRNA 及蛋白表达,其中ADM(10^-8mol/L)组中 TGFβ1 mRNA 及蛋白表达分别抑制了55%和45%（P<0.01）,ADM(10^-7mol/L)组则分别抑制了70%和59%（P<0.01）;AngⅡ明显下调细胞内 MMP-2 mRNA 及蛋白表达,ADM 呈剂量依赖性抑制上述作用,其中10^-8mol/L ADM 组细胞内 MMP-2 mRNA 及蛋白表达分别增加了1.0和0.9倍。结论 AngⅡ可刺激血管外膜成纤维细胞释放 ADM,而自分泌旁分泌的 ADM 可能通过下调细胞内 TGFβ1表达和上调 MMP-2表达,抑制 AngⅡ刺激的Ⅰ、Ⅲ型胶原蛋白生成,从而发挥有效的抗血管重构作用。更多还原

【Abstract】 Objective To explore the effects of adrenomedullin（ADM）on Angiotensin Ⅱ（Ang Ⅱ）-induced collagen synthesis in cultured rat vascular adventitial fibroblasts.Methods Rat vascular adventitial fibroblasts were cultured in vitro.ADM produced and secreted from adventitia in the presence of Ang Ⅱ was detected by radioimmunoassay,type Ⅰ,Ⅲ collagen contents in adventitia fibroblasts were measured by ELISA and the expressions of TGFβ1 and MMP-2 were determined by RT-PCR and Western blotting.Results Ang Ⅱ significantly induced ADM secretion in adventitial fibroblasts in a dose-dependent manner.These effects could be reduced by 45%,3% and 46%,through pre-treatment with Losartan, PD123319 or both,respectively for 30 rain in culture medium.The Ang Ⅱ-induced type Ⅰ,Ⅲ collagen secretion in adventitial fibroblasts was significantly reduced by AMD in a dose-dependent manner,（P< 0.01）while ADM agonist ADM_22-52significantly potentiated the effect of Ang Ⅱ;ADM also reduced Ang Ⅱ- induced expression of TGFβ1 at mRNA and protein levels in a dose-dependent manner.Ang Ⅱ reduced the expression of MMP-2 at mRNA and protein levels in adventitial fibroblasts and these effects could be reversed by AMD(10^-8mol/L).Conclusion Ang Ⅱ stimulated ADM secretion in adventitia fibroblasts,ADM in turn can inhibit Ang Ⅱ-induced type Ⅰ,Ⅲ collagen synthesis in adventitial fibroblasts probably by downregulating the TGFβ1 expression and upregulating MMP-2 expression.ADM therefore served as an antifibrotic factor in vascular remodeling process.更多还原