Canine bile contains anticrystallization factors that inhibit precipitation of calcium carbonate.
Canine bile contains anticrystallization factors that inhibit precipitation of calcium carbonate.
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犬胆汁含有抑制碳酸钙沉淀的抗结晶因子。
DOI：
10.1016/0270-9139(91)90061-y
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发表时间：
1991
期刊：
影响因子：
--
通讯作者：
Ostrow,JD
中科院分区：
文献类型：
--
作者：
Dawes,LG;Moore,EW;Rege,RV;Shimizu,S;Ostrow,JD
先前的研究强烈表明，人胆汁中含有一种干扰磷酸钙和碳酸钙从溶液中沉淀的物质。然而，这些研究没有区分胆汁成分导致碳酸钙饱和度降低（溶液热力学改变）的钙结合和动力学因素对钙盐沉淀的真正抑制。由于我们最近的研究表明，犬胆总管胆汁中碳酸钙总是过饱和的（有沉淀的危险），我们假设它一定含有抑制碳酸钙晶体形成和/或生长的动力学因素。在自发进行快速沉淀的高度过饱和碳酸钙溶液中，研究了犬胆汁、牛白蛋白和牛磺胆酸盐对碳酸钙沉淀的影响。比较供试品溶液和对照品中测定的游离离子钙浓度[Ca++]和计算的碳酸钙饱和指数，以评价供试品溶液对测定系统中饱和度的热力学影响。结果表明，仅向测定系统中加入0.2 ml正常犬胆囊胆汁（胆汁组分的1：101稀释液）即可消除沉淀。当胆囊胆汁被稀释时，观察到较小的抑制作用（沉淀率降低），但在10倍稀释后消失。犬胆总管胆汁引起沉淀率下降，与稀释的胆囊胆汁相似。相比之下，牛磺胆酸钠（250 mmol/L）（犬的主要胆汁盐）和白蛋白（1.5 gm/L）（胆汁中含量最丰富的蛋白质）仅具有极轻微的抑制作用。我们的结论是，正常胆汁中含有抑制碳酸钙沉淀和防止含钙胆结石的动力学因素。这些影响不是由于碳酸钙饱和度的变化，而是由于沉淀动力学的改变。（Hepatology 1991; 14：701-706.）
Previous studies have strongly suggested that human bile contains a substance (s) that interferes with the precipitation of calcium phosphate and carbonate from solution. These studies, however, did not distinguish between calcium binding by biliary constituents resulting in decreased calcium carbonate saturation (alterations in solution thermodynamics) and true inhibition of calcium salt precipitation by kinetic factors. Because our recent studies have shown that canine common duct bile is always supersaturated with calcium carbonate (thermodynamically at risk for precipitation), we hypothesized that it must contain kinetic factors that inhibit formation and/or growth of calcium carbonate crystals. Effects of canine bile, bovine albumin and the bile salt taurocholate on calcium carbonate precipitation were studied in highly supersaturated solutions of calcium carbonate that spontaneously undergo rapid precipitation. Measured free ionized calcium concentrations,[Ca++], and calculated calcium carbonate saturation indices were compared in test solutions and controls to evaluate the thermodynamic effects of test solutions on the degree of saturation in the assay system. It is shown that addition of only 0.2 ml of normal canine gallbladder bile to the assay system (a 1: 101 dilution of biliary components) abolished precipitation. A lesser inhibitory effect (a decrease in the rate of precipitation) was observed when gallbladder bile was diluted but was lost after 10-fold dilution. Canine common duct bile caused a decrease in the rate of precipitation similar to diluted gallbladder bile. In contrast, sodium taurocholate (250 mmol/L), the major bile salt in the dog, and albumin (1.5 gm/L), the most abundant protein in bile, had only a minimal inhibitory effect. We conclude that normal bile contains kinetic factors that inhibit calcium carbonate precipitation and protect against calcium-containing gallstones. These effects are not due to changes in calcium carbonate saturation but rather to alterations in precipitation kinetics.(Hepatology 1991; 14: 701-706.)