Ridgeway R D, MacGregor R R
Veterans Administration Medical Center, Kansas City, Missouri 64128.
Am J Physiol. 1988 Mar;254(3 Pt 1):E279-86. doi: 10.1152/ajpendo.1988.254.3.E279.
Aggregates of bovine parathyroid cells (organoids) were cultured with or without 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] and examined for effects on the synthesis, cellular content, and release of parathyroid hormone (PTH) and secretory protein I. Organoids cultured with 120 pM 1,25(OH)2D3 at 1.35 mM calcium contained 27 +/- 2% (mean +/- SE) less and released 26 +/- 7% less PTH and contained 21 +/- 2% more and released 49 +/- 16% more secretory protein I than untreated organoids. After 15-min incubations with radioactive leucine, treated organoids incorporated 25 +/- 2% less radioactivity into precipitable cellular proteins than did untreated organoids, indicating that the overall synthetic rate of proteins was decreased by 1,25(OH)2D3 at 1.35 mM calcium. After separation of cellular proteins by gel electrophoresis, analysis of individual protein bands indicated that the mean treated-control ratio for proparathyroid hormone radioactivity was 0.88 +/- 0.06 (P less than 0.10) while that for secretory protein I was 1.56 +/- 0.17 (P less than 0.01), respectively. Experiments were performed at 1.2, 12, 120, and 1,200 pM 1,25(OH)2D3 and both 1.4 and 1.8 mM calcium. In both cases, increasing levels of 1,25(OH)2D3 progressively decreased PTH synthesis and release and progressively increased that of secretory protein I, significant effects being observed at 1.2 pM 1,25(OH)2D3. We conclude that at physiological calcium levels, 1.2-1,200 pM 1,25(OH)2D3 suppresses the synthesis and secretion of PTH, increases that of secretory protein I, and at similar concentrations decreases the overall protein synthetic rate compared with untreated controls.
将牛甲状旁腺细胞聚集体（类器官）在添加或不添加1,25 - 二羟维生素D3 [1,25(OH)2D3]的情况下进行培养，并检测其对甲状旁腺激素（PTH）和分泌蛋白I的合成、细胞含量及释放的影响。在1.35 mM钙浓度下，用120 pM 1,25(OH)2D3培养的类器官，其PTH含量比未处理的类器官少27±2%（平均值±标准误），释放量少26±7%，而分泌蛋白I的含量多21±2%，释放量多49±16%。在用放射性亮氨酸孵育15分钟后，与未处理的类器官相比，经处理的类器官掺入可沉淀细胞蛋白中的放射性少25±2%，这表明在1.35 mM钙浓度下，1,25(OH)2D3降低了蛋白质的整体合成速率。通过凝胶电泳分离细胞蛋白后，对各个蛋白条带的分析表明，甲状旁腺激素原放射性的平均处理组与对照组比值为0.88±0.06（P＜0.10），而分泌蛋白I的比值为1.56±0.17（P＜0.01）。实验在1.2、12、120和1200 pM 1,25(OH)2D3以及1.4和1.8 mM钙浓度下进行。在这两种情况下，1,25(OH)2D3水平的升高均使PTH的合成和释放逐渐减少，使分泌蛋白I的合成和释放逐渐增加，在1.2 pM 1,25(OH)2D3时观察到显著影响。我们得出结论，在生理钙水平下，1.2 - 1200 pM 1,25(OH)2D3抑制PTH的合成和分泌，增加分泌蛋白I的合成和分泌，并且在相似浓度下与未处理的对照组相比降低了整体蛋白质合成速率。
