钠离子对成骨细胞的影响及其与上皮钠通道的关系

Effects of sodium on rat osteoblast and the role of epithelial sodium channel

探讨不同浓度钠离子（Na ＋ ）对大鼠成骨细胞（Ob）成骨功能的影响，及其与上皮钠通道（ENaC）的相关性。方法 Ob经1×10 -4 ~1 mol/L Na ＋ 处理后，检测Ob的增殖和分化情况。再从中选3个浓度Na ＋ 处理Ob，RT-PCR测定成骨功能相关基因（Cbfa1，OPN，OC）及ENaC-α的表达变化。结果 在1×10 -4 ~1 mol/L范围内，Na ＋ 对Ob具有双向影响作用，与对照组相比低浓度Na ＋ 明显促进Ob分化，升高Na＋浓度则抑制Ob分化，而Na＋对Ob的增殖无影响。RT-PCR示：Na ＋ 对Ob中 Cbfa1、OPN 及 OC 表达同样具有双向作用，低浓度促进表达，高浓度抑制；并且 ENaC-α mRNA 在 Na ＋ 调控下的变化情况与成骨功能相关基因及Ob分化活性的变化相一致。 结论 Na ＋ 可直接影响Ob的分化及成骨功能相关基因的表达，而且 Na ＋ 对Ob的影响作用与ENaC相关。

Objective To study the effects of sodium on rat osteoblast function and explore the role of epithelial sodium channel（ENaC） in such effects.Methods The proliferation and differentiation of rat osteoblasts were evaluated following treatment with 1×10-4 to 1 mol/L Na＋.The mRNA expressions of the osteogenic genes and ENaC-α gene in the treated cells were assessed using RT-PCR.Results Within the concentration of 1×10-4 to 1 mol/L,Na＋ showed a two-way effect on the osteoblasts： low-concentration Na＋（1×10-4 mol/L） significantly promoted osteoblast differen-tiation,while at higher concentrations（0.5 and 1 mol/L）,Na＋ produced an opposite effect.Sodium did not significantly affect osteoblast proliferation.Low-concentration Na＋ significantly increased the transcription of Cbfa1,OPN and OC,while high concentrations of Na＋ decreased their transcription.Low-concentration Na＋ also enhanced the mRNA expression of ENaC-α,but high-concentration Na＋ treatment lowered ENaC-α mRNA expression.Conclusion Na＋ displays a direct dose-related effect on osteoblasts by affecting its differentiation,osteogenic gene expression profile,and ENaC-α gene expression,suggesting the involvement of ENaC in Na＋-mediated functional modulation of rat osteoblasts.