Li Lu1, Liang Wu, Jun Chen, Xiao-hui Lin, Chao Wan, Qing-nan Li. 1. Guangdong Key Laboratory of Pharmaceutical Bioactive Substances, School of Life Science and Biopharmacy, Guangdong Pharmaceutical University, Guangzhou 510006, China.
Abstract
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) mol/L 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) mol/L 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.
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) mol/L 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) mol/L 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.