FORMATION OF OCTACALCIUM PHOSPHATE AND SUBSEQUENT TRANSFORMATION TO HYDROXYAPATITE AT LOW SUPERSATURATION - A MODEL FOR CARTILAGE CALCIFICATION
FORMATION OF OCTACALCIUM PHOSPHATE AND SUBSEQUENT TRANSFORMATION TO HYDROXYAPATITE AT LOW SUPERSATURATION - A MODEL FOR CARTILAGE CALCIFICATION
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DOI：
10.1007/bf02556696
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发表时间：
1987-06-01
影响因子：
4.2
通讯作者：
CHENG, PT
中科院分区：
文献类型：
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作者：
CHENG, PT
通过x射线粉末衍射（XRD）分析，发现磷酸八钙(OCP, Ca8H2(PO4)6 .cntdot。在含有[CaCl2] = 1.0-2.0 mM和[Na2HPO4]的水溶液中，5H2O, Ca/P = 1.33)被证明是羟基磷灰石(HA, Ca10（PO4)6(OH)2, Ca/P = 1.67）在新生HA形成过程中的亚稳前体。3毫米，保持在37度。C, 300 mosM，以150 rpm的转速轻轻搅拌。在初始pH = 7.4的降水边界，当[Ca] = 1.0 mM时，OCP至少稳定24小时，当[Ca] = 2.0 mM时，OCP稳定性较差，在24小时内转变为OCP和HA的混合物。在高[Ca]和高[Pi]条件下，24小时内几乎完全转化为HA。对pH 7.4沉淀边界数据的统计分析支持XRD的发现：尽管[Ca][Pi]值随[Ca]（2.70 .+-）变化显著（P < 0.001）。0.05 mM2 [Ca] = 1.0 mM和2.00 .+-。[Ca] = 2.0 mM时为0.10 mM2, [Ca]1.33[Pi]值不随[Ca]变化，表明初始降水过程为6（1.33 Ca + Pi）。(OCP。当初始pH = 7.6时，确定了具有较低[Ca][Pi]值的不同降水边界。这些发现有力地支持了这样一个事实，即大鼠骺软骨液[CaUF][PiUF] = 2.6 mM2 （UF =超滤液）和pH 7.6[2]应该能够支持新生钙化。
By means of X-ray powder diffraction (XRD), octacalcium phosphate (OCP, Ca8H2(PO4)6 .cntdot. 5H2O, Ca/P = 1.33) has been shown to be a metastable precursor of hydroxyapatite (HA, Ca10(PO4)6(OH)2, Ca/P = 1.67) during de novo HA formation in aqueous solutions containing [CaCl2] = 1.0-2.0 mM and [Na2HPO4] .ltoreq. 3 mM, kept at 37.degree. C, 300 mosM and stirred gently at 150 rpm. At the precipitation boundary with initial pH = 7.4, OCP is stable for at least 24 hours when [Ca] = 1.0 mM, and is less stable when [Ca] = 2.0 mM, transforming into a mixture of OCP and HA within 24 hours. Almost complete transformation to HA within 24 hours takes place with high [Ca] and high [Pi]. Statistical analysis of the pH 7.4 precipitation boundary data supports the XRD findings: although [Ca][Pi] values vary significantly (P < 0.001) with [Ca] (2.70 .+-. 0.05 mM2 for [Ca] = 1.0 mM and 2.00 .+-. 0.10 mM2 for [Ca] = 2.0 mM), [Ca]1.33[Pi] values do not vary with [Ca] suggesting that the initial precipitation process is 6(1.33 Ca + Pi) .fwdarw. OCP. With initial pH = 7.6, a different precipitation boundary with lower [Ca][Pi] values has been determined. These findings strongly support the fact that rat epiphyseal cartilage fluid which has [CaUF][PiUF] = 2.6 mM2 (UF = ultrafiltrate) and pH 7.6 [2] should be able to support de novo calcification.