Cunningham J, Coldwell R D, Jones G, Tenenhouse H S, Trafford D J, Makin H L
Department of Nephrology, London Hospital and Medical College, United Kingdom.
J Bone Miner Res. 1990 Feb;5(2):173-7. doi: 10.1002/jbmr.5650050211.
Previous studies have suggested that both plasma 24,25-dihydroxyvitamin D [24,25-(OH)2D] concentrations and renal 25-hydroxyvitamin D-24-hydroxylase activity are increased in mice with X-linked hypophosphatemia (Hyp mice). However, because the plasma levels of 24,25-(OH)2D seemed surprisingly high, we repeated these assays using two different techniques. Mass fragmentographic and radioreceptor assays were employed to compare the plasma concentrations of 25-hydroxyvitamin D (25-OHD) and 24,25-(OH)2D in normal mice with those in Hyp mice. These assays yielded 24,25-(OH)2D concentrations much lower than previously reported in mice (both normal and Hyp). The concentrations of 25-OHD3 and 24,25-(OH)2D3, determined by mass fragmentography, were lower in Hyp mice than in controls [25-OHD3, 9.7 +/- 0.4 versus 14.6 +/- 0.6 ng/ml, p less than 0.01; 24,25-(OH)2D3, 7.1 +/- 0.3 versus 10.4 +/- 0.4 ng/ml, p less than 0.01]. Plasma 25-OHD concentration was the main determinant of plasma 24,25-(OH)2D, and the ratio of 25-OHD3 to 24,25-(OH)2D3 obtained from mass fragmentographic measurements did not differ between the two groups (1.40 +/- 0.05 versus 1.36 +/- 0.03 ng/ml, NS in normal and Hyp groups, respectively). Separate measurement of plasma 25-OHD, 24,25-(OH)2D, and 25-OHD3-26,23-lactone by radioreceptor assay showed no difference between either plasma 24,25-(OH)2D, or the ratio of 25-OHD concentration to 24,25-(OH)2D concentration among Hyp and control animals. In neither study was plasma phosphate concentration related to the 25-OHD3:24,25-(OH)2D3 ratio.(ABSTRACT TRUNCATED AT 250 WORDS)
先前的研究表明，X连锁低磷血症小鼠（Hyp小鼠）的血浆24,25-二羟基维生素D[24,25-(OH)2D]浓度和肾脏25-羟基维生素D-24-羟化酶活性均升高。然而，由于24,25-(OH)2D的血浆水平似乎出奇地高，我们使用两种不同技术重复了这些检测。采用质量碎片分析法和放射受体分析法比较正常小鼠和Hyp小鼠血浆中25-羟基维生素D（25-OHD）和24,25-(OH)2D的浓度。这些检测得出的24,25-(OH)2D浓度远低于先前报道的小鼠（正常和Hyp）中的浓度。通过质量碎片分析法测定，Hyp小鼠中25-OHD3和24,25-(OH)2D3的浓度低于对照组[25-OHD3，9.7±0.4对14.6±0.6 ng/ml，p<0.01；24,25-(OH)2D3，7.1±0.3对10.4±0.4 ng/ml，p<0.01]。血浆25-OHD浓度是血浆24,25-(OH)2D的主要决定因素，通过质量碎片分析测量得到的25-OHD3与24,25-(OH)2D3的比值在两组之间没有差异（正常组和Hyp组分别为1.40±0.05对1.36±0.03 ng/ml，无显著性差异）。通过放射受体分析法单独测量血浆25-OHD、24,25-(OH)2D和25-OHD3-26,23-内酯，结果显示Hyp小鼠和对照动物之间的血浆24,25-(OH)2D或25-OHD浓度与24,25-(OH)2D浓度的比值均无差异。在两项研究中，血浆磷酸盐浓度均与25-OHD3:24,25-(OH)2D3比值无关。（摘要截断于250字）
