上皮钠离子通道对大鼠破骨细胞分化和骨吸收功能的影响

目的本文探讨上皮钠离子通道（ENaC）对破骨细胞功能和活性的影响。方法采用大鼠巨噬细胞集落刺激因子和核转录 因子-κB受体活化因子配体诱导大鼠骨髓单核细胞使其分化为破骨细胞。以1.5×104密度接种到12孔板，查随机表分3孔为1 组，分为4组：Control组和不同浓度阿米洛利（Ami, ENaC的抑制剂）组。抗酒石酸酸性磷酸酶（TRAP）染色进行阳性破骨细胞 鉴定；将破骨细胞和骨片共同培养，测定骨吸收陷窝的数目；用RT-PCR技术分析破骨细胞标志酶基因组织蛋白酶K（CK）的表 达。结果不同浓度的Ami处理破骨细胞后，TRAP染色阳性破骨细胞减少，抑制破骨细胞的形成和骨吸收，而且降低破骨细胞 特异性基因CK的表达。结论本次实验在细胞水平证明ENaC在破骨细胞上的表达并且调控破骨细胞的分化和骨吸收，说明 ENaC可能参与破骨细胞的功能调节，提示破骨细胞可能存在一个与ENaC相关调节的新途径，为骨代谢的研究提供了一个新 思路。

Role of epithelial sodium channel in rat osteoclast differentiation and bone resorption

Objective To explore the role of epithelial sodium channel (ENaC) in regulating the functional activity of osteoclasts. Methods Multinucleated osteoclasts were obtained by inducing the differentiation of rat bone marrow cells with macrophage colony-stimulating factor (M-CSF) and RANKL. The osteoclasts were exposed to different concentrations of the ENaC inhibitor amiloride, and the expression of ENaC on osteoclasts was examined using immunofluorescence technique. The osteoclasts were identified with tartrate-resistant acid phosphatase (TRAP) staining, and the positive cells were incubated with fresh bovine femoral bone slices and the number of bone absorption pits was counted by computer-aided image processing. RT-PCR was performed to analyze the expression of cathepsin K in the osteoclasts. Results Exposure to different concentrations of amiloride significantly inhibited the expression of ENaC and reduced the number of TRAP-positive osteoclasts. Exposure of the osteoclasts to amiloride also reduced the number of bone resorption pits on bone slices and the expression of osteoclast-specific gene cathepsin K. Conclusions ENaC may participate in the regulation of osteoclast differentiation and bone resorption, suggesting its role in functional regulation of the osteoclasts and a possibly new signaling pathway related with ENaC regulation for modulating bone metabolism.