Kabakoff B, Kendrick N C, DeLuca H F
Am J Physiol. 1982 Dec;243(6):E470-5. doi: 10.1152/ajpendo.1982.243.6.E470.
An assay system for measuring an active phosphate uptake in rat jejunal disks has been developed and used to study the rat's response to 1,25-dihydroxyvitamin D3. The active component of phosphate uptake is stimulated by added KCl, fructose, sodium, and CaCl2, but not MgCl2. Half-saturation values obtained with this assay are 0.08 mM (1,25-dihydroxyvitamin D3-treated) and 0.11 mM (D-deficient). The maximal velocities are 9.6 nmol . cm-2 . min-1 (D-deficient). Using a 5-min preincubation and a 15-min incubation, a dose-response curve for 1,25-dihydroxyvitamin D3 shows 6 pmol to be the lowest dose to give a significant response and 60 pmol to be the level at which the maximal response is reached. Measurement of phosphate uptake versus time after dosing with 1,25-dihydroxyvitamin D3 (300 pmol) revealed a biphasic response with peaks at 8 and 36 h and a trough at 20 h.
已开发出一种用于测量大鼠空肠盘片中活性磷酸盐摄取的检测系统，并用于研究大鼠对1,25 - 二羟基维生素D3的反应。添加氯化钾、果糖、钠和氯化钙可刺激磷酸盐摄取的活性成分，但氯化镁则无此作用。用该检测方法获得的半饱和值为0.08 mM（1,25 - 二羟基维生素D3处理组）和0.11 mM（维生素D缺乏组）。最大速度为9.6 nmol·cm-2·min-1（维生素D缺乏组）。采用5分钟预孵育和15分钟孵育，1,25 - 二羟基维生素D3的剂量反应曲线显示，6皮摩尔是产生显著反应的最低剂量，60皮摩尔是达到最大反应的剂量水平。在给予1,25 - 二羟基维生素D3（300皮摩尔）后测量磷酸盐摄取随时间的变化，结果显示为双相反应，在8小时和36小时出现峰值，在20小时出现谷值。
