内皮素受体阻断剂抑制磷酸甘油诱导血管平滑肌细胞钙化

目的：在离体钙化的血管平滑肌细胞上，观察内皮素受体阻断剂对血管平滑肌细胞(VSMCs)钙化的影响，探讨内皮素(ET)促进细胞钙化的信号转导和分子机制。方法：β-磷酸甘油制备钙化VSMCs；通过细胞钙含量,［45Ca2+］摄取，碱性磷酸酶活性测定，判断钙化程度，［3H］-胸腺嘧啶（［3H］-TdR）和［3H］-亮氨酸（［3H］-Leu）掺入测定细胞DNA合成，竞争性定量RT-PCR测定VSMCs骨桥蛋白 （OPN） mRNA水平，放射免疫法测定培养上清ET含量。结果: 与正常对照VSMCs相比，钙化VSMCs内钙含量，［45Ca2+］摄入及碱性磷酸酶活性分别增加 119%、174%和7倍（P<0.01），OPN表达增加86%；细胞生长活跃，［3H］-TdR和［3H］-Leu分别增加71%和35%；钙化细胞培养基中内皮素含量较对照组增加35%(P<0. 05)。而钙化加内皮素受体阻断剂BQ123组明显减轻VSMCs钙化程度，钙含量，［45Ca2+］摄入及碱性磷酸酶活性分别较钙化组降低33%、37%、40%（均P<0.01），OPN表达明显下调25%；细胞增殖活性明显降低。结论: BQ123可减轻VSMCs钙化程度，表明ET促进VSMCs钙化主要是通过内皮素A型受体（ET-A）途经。

Endothelin receptor antagonist BQ123 inhibits calcification in vascular smooth muscle cells induced by β-glycerophosphate

AIM:To observe the effect of endothelin receptor antagonist (BQ123) on calcification in rat vascular smooth muscle cells (VSMCs) in vitro. METHODS:Calcification of cultured rat VSMCs was produced by incubation with β-glycerophosphate. Calcium content, Ca2+ deposition and alkaline phosphatase activity were analyzed to estimate the extent of calcification. The DNA synthesis was detected by ［3H］ -TdR and ［3H］-Leu incorporation. Osteopontin (OPN) mRNA was measured by competitive quantitative RT-PCR. Content of ET was measured by radioimmunoassay (RIA). RESULTS:The results showed that compared with the control, the content of calcium, ［45Ca2+］ uptake and alkaline phosphatases activities in calcified VSMCs increased by 118%, 174% and 7-fold (all P<0.01), respectively. The expression of OPN mRNA in calcified VSMCs was up-regulated by 86% (P<0.01). The calcified VSMCs grew rapidly, in which ［3H］-TdR and ［3H］-Leu were elevated by 71% and 35%. The content of ET in calcified VSMCs medium was increased by 35% as compared with control. Furthermore, calcified VSMCs plus BQ123 groups obviously relieved degree of calcification, of which calcium content, Ca2+ deposition and alkaline phosphatase activities were 33%, 37%, 40% lower than those in calcified VSMCs (P<0.01), respectively. The expression of OPN mRNA was down-regulated by 25% (P<0.01) and significantly inhibited VSMCs proliferation. CONCLUSION:BQ123 reduces VSMCs calcification, suggesting that ET promotes calcification in VSMCs mainly by ET/ ETA receptor pathway.