摘要：
Objective To explore the effect and mechanism of magnesium on calcification induced by hyperphosphate.Methods Vascular smooth muscle cells (VSMCs) were primarily cultured in vitro and induced calcification by β-glycerophosphate (β-GP).VSMCs were randomly divided into control group,high phosphorus group (10 mmol/L β-GP),magnesium intervèntion group(10 mmol/L β-GP + 3 mmol/L MgSO4) and 2-aminoethoxy-diphenylborate (2-APB,an inhibitor of magnesium transporter) intervention group(10 mmol/L β-GP+3 mmol/L MgSO4+ 10-4 mol/L 2-APB).Calcium deposition and alkaline phosphatase (ALP) activity were measured by alizarin red staining,quantification of calcium and euzyme linked immunosorbent assay.RT-PCR and Western blotting were used to observe the expression of core binding factor α-1 (Cbfα-1) mRNA and protein,respectively.In vivo,male Sprague-Dawley rats (n=24) were randomly divided into control group (methylcellulose+high phosphorous diet),vascular calcification group (adenine suspension + high phosphorous diet),high magnesium intervention group(adenine suspension+high phosphorous and magnesium diet).The aortic pulse wave velocity (PWV) was measured,and vascular calcification was determined by von Kossa stain and quantification of calcium.Cbfα-1 in aortic was measured by immunohistochemistry.Results In vitro,compared with high phosphorus group,calcification,ALP activity (P ＜ 0.05) and Cbfα-1expression in VSMCs were significantly decreased in magnesium intervention group after incubation for 14 days,but the addition of 2-APB might inhibit the protective effect of magnesium on VSMCs.Dynamic observation of Cbfα-1 showed that magnesium significantly inhibited the expression of Cbfα-1 (P ＜ 0.05) on the third day and the inhibitory role was obviously increased in a time-dependent manner.Consistent with the findings in vitro,the aortic PWV,calcification were all significantly reduced (P ＜ 0.05) in high magnesium intervention group with high serum magnesium level,when compared with vascular calcification group.Immunohistochemistry showed that hypermagnesemia downregulated obviously the expression of Cbfα-1 induced by hyperphosphatemia(P ＜ 0.05).Conclusion Magnesium protects against vascular calcification by inhibiting osteogenic differentiation of VSMCs.%目的 探讨高镁对高磷诱导血管钙化的影响及其可能的机制.方法 体外原代培养大鼠胸主动脉血管平滑肌细胞(VSMCs),用β甘油磷酸盐(β-GP)诱导钙化.VSMCs细胞被分为4组:对照组、高磷组(10 mmol/L β-GP)、镁干预组(10 mmol/L β-GP+3 mmol/LMgSO4)、镁通道抑制剂(2-APB)干预组(10 mmol/L β-GP+3 mmol/L MgSO4+10-4 mol/L 2-APB).采用茜素红染色及邻甲酚酞络合酮比色法检测细胞钙化情况;酶联免疫吸附法(ELISA)检测细胞碱性磷酸酶(ALP)活性;RT-PCR法和Western印迹法检测细胞核心结合因子α-1(Cbfα-1)的表达.24只雄性SD大鼠被随机分为3组:对照组(甲基纤维素灌胃+高磷饮食)、血管钙化组(硫酸腺嘌呤灌胃+高磷饮食)、高镁干预组(硫酸腺嘌呤灌胃+高磷高镁饮食).造模成功后测定大鼠主动脉脉搏波速率(PWV);采用yon Kossa染色及邻甲酚酞络合酮比色法检测胸主动脉钙化情况;免疫组织化学方法检测胸主动脉Cbfα-1表达.结果 细胞培养14 d后,与高磷组相比,镁干预组VSMCs钙盐沉积明显减少,ALP活性降低(P＜0.05),Cbfα-1表达下调;2-APB可抑制高镁对VSMCs的保护性作用.Cbfα-1的动态观察结果显示,镁干预组第3天Cbfα-1的表达下调(P＜0.05),其抑制效应随时间延长呈增强趋势.体内实验中,大鼠慢性肾衰竭血管钙化模型制备成功.和体外实验一致,与血管钙化组相比,高镁干预组大鼠血浆镁离子水平明显升高,胸主动脉PWV明显降低(P＜0.05),血管钙盐沉积程度亦明显减轻.免疫组织化学结果显示高镁可明显降低高磷诱导的Cbfα-1表达(P＜0.05).结论 高镁可抑制血管钙化,其机制可能与其抑制VSMCs骨源性分化相关.
