van den Bos T, Oosting J, Everts V, Beertsen W
Department of Periodontology, Academic Center for Dentistry Amsterdam (ACTA), The Netherlands.
J Bone Miner Res. 1995 Apr;10(4):616-24. doi: 10.1002/jbmr.5650100415.
The present study was designed to determine the relationship between mineralization of collagenous matrices and serum levels of calcium and inorganic phosphate. Collagen slices were prepared from bovine dentin or cortical bone and complexed with varying amounts of intestinal alkaline phosphatase (ALP). The enzyme was added to induce de novo mineralization. The ALP-complexed slices were implanted subcutaneously over the skull and in the dorsolateral aspect of the abdominal wall in female Wistar rats of various ages (5-, 10-, 20-, or 35-week-old) and in young male rats fed on a low-P diet. After 1-4 weeks, the implants were removed and analyzed for calcium and phosphate content. In addition, serum levels of calcium and phosphate (total and inorganic) were determined. It was shown that the highest mineral influx occurred in the younger rats (which were also highest in serum P(i)), whereas almost no mineral uptake occurred in the older ones. Also in rats fed on a low-P diet (which were low in serum P(i), a strongly decreased mineral influx was noted. In all animal groups a positive correlation was found between the degree of mineralization and serum P(i). No distinct relationship was found between serum Ca/organic phosphate levels and mineral influx in the implants. In vitro incubation of ALP-collagen conjugates in serum from younger and older rats confirmed our view that serum P(i), besides local levels of ALP, is important in de novo mineral deposition. For accretion of mineral in partially remineralized collagenous carriers, ALP activity was not required.
本研究旨在确定胶原基质矿化与血清钙和无机磷水平之间的关系。从牛牙本质或皮质骨制备胶原切片，并与不同量的肠碱性磷酸酶（ALP）复合。加入该酶以诱导从头矿化。将ALP复合切片皮下植入不同年龄（5周、10周、20周或35周）的雌性Wistar大鼠的颅骨上方和腹壁背外侧，以及喂食低磷饮食的年轻雄性大鼠体内。1-4周后，取出植入物并分析钙和磷含量。此外，测定血清钙和磷（总钙和无机磷）水平。结果表明，矿物质流入量最高的是较年轻的大鼠（其血清无机磷水平也最高），而较年长的大鼠几乎没有矿物质摄取。同样，在喂食低磷饮食的大鼠中（其血清无机磷水平较低），矿物质流入量也显著降低。在所有动物组中，矿化程度与血清无机磷之间均呈正相关。未发现血清钙/有机磷水平与植入物中的矿物质流入之间存在明显关系。在年轻和年长大鼠的血清中对ALP-胶原缀合物进行体外孵育，证实了我们的观点，即血清无机磷除了局部ALP水平外，在从头矿物质沉积中也很重要。对于部分再矿化的胶原载体中的矿物质积聚，不需要ALP活性。
