TNF-α、IL-1β及LPS对血管平滑肌细胞一氧化氮合酶基因表达的影响及作用机制研究

通过ＲＮＡ印迹分析和亚硝酸盐含量测定检查ＴＮＦ－α、ＩＬ－１β和ＬＰＳ对大鼠血管平滑肌细胞（ＶＳＭＣ）诱导型一氧化氮合酶（ｉＮＯＳ）基因表达及ＮＯ生成的影响．结果表明，ＴＮＦ－α、ＩＬ－１β和ＬＰＳ均能显著诱导ＶＳＭＣｉＮＯＳ基因表达和促进ＮＯ生成，其作用强度与浓度和作用时间有关；双因素（ＴＮＦ－α＋ＬＰＳ，ＬＰＳ＋ＩＬ－１β）对诱导ｉＮＯＳ基因表达及ＮＯ生成产生协同作用．ＰｏｌｙｍｙｘｉｎＢ和地塞米松可部分抑制ＴＮＦ－α对ｉＮＯＳ基因表达的诱导作用及ＮＯ生成

Study on the Expression of Nitric Oxide Synthase Gene and Regulation Mechanism in VSMC Influenced

To identify which of tumor necrosis factor α(TNF α),interleukin 1β(IL 1β)and lipopolysaccharide(LPS),if any,was acting to induce the gene expression of nitric oxide synthase(NOS) in rat vascular smooth muscle cells (VSMC),the levels of inducible NOS(iNOS) mRNA in VSMC and the concentrations of supernatant nitrite were measured after stimulation by single cytokines and combination of two cytokines.It was found that TNF α,IL 1β and LPS induced iNOS mRNA expression in VSMC in a dose dependent manner.The time course of VSMC iNOS induction was related with the kind of cytokines.Abundance of iNOS mRNA peaked at 12 h exposure to LPS.TNF α continually increased iNOS mRNA levels up to 24 h.Combination of two cytokines(TNF α+LPS,LPS+IL 1β)synergistically induced iNOS gene expression in VSMC.The elevated nitrite in the culture supernatants basically correlated with the increased mRNA levels.Protein kinase C(PKC) inhibitor polymyxin B partly inhibited the induction of iNOS mRNA and NO production in VSMC both before and after the addition of TNF α.The effects of dexamethasone on iNOS mRNA expression and NO generation were mimicked by the treatment of polymyxin B.