Giuliani D L, Boland R L
Calcif Tissue Int. 1984 Mar;36(2):200-5. doi: 10.1007/BF02405318.
25-hydroxycholecalciferol (25OHD3) and 1,25-dihydroxycholecalciferol (1,25(OH)2D3) at physiological concentrations exerted direct effects on Ca fluxes in cultured vitamin D-deficient chick soleus muscle and myoblasts. Isotopic desaturation curves of soleus muscle prelabeled with 45Ca indicated that the action of 25OHD3 is localized in a slow-exchangeable Ca pool where it stimulates net Ca uptake. On the other hand, the predominant effects of 1,25(OH)2D3 consist in an increase of the rate constant of Ca efflux of this pool and in an increase of net Ca uptake in a fast-exchangeable pool. 24,25-dihydroxycholecalciferal proved to be inactive on both Ca uptake and efflux. In addition, 1,25(OH)2D3 significantly increased 45Ca labeling of cultured chick myoblasts. These effects were accompanied by changes in the growth and differentiation of the cultures. The results suggest a direct involvement in vivo of 25OHD3 and 1,25(OH)2D3 on muscle cellular calcium.
生理浓度的25-羟基胆钙化醇（25OHD3）和1,25-二羟基胆钙化醇（1,25(OH)2D3）对培养的维生素D缺乏的雏鸡比目鱼肌和成肌细胞中的钙通量有直接影响。用45Ca预标记的比目鱼肌的同位素去饱和曲线表明，25OHD3的作用定位于一个缓慢交换的钙池中，它在该池中刺激净钙摄取。另一方面，1,25(OH)2D3的主要作用在于增加该池钙流出的速率常数以及增加快速交换池中净钙摄取。24,25-二羟基胆钙化醇被证明对钙摄取和流出均无活性。此外，1,25(OH)2D3显著增加了培养的雏鸡成肌细胞的45Ca标记。这些作用伴随着培养物生长和分化的变化。结果表明，25OHD3和1,25(OH)2D3在体内直接参与肌肉细胞钙代谢。
