Quasielastic light scattering evidence for vesicular secretion of biliary lipids.
Quasielastic light scattering evidence for vesicular secretion of biliary lipids.
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胆汁脂质囊泡分泌的准弹性光散射证据。
DOI：
10.1152/ajpgi.1989.257.1.g1
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发表时间：
1989
期刊：
影响因子：
--
通讯作者：
Carey,MC
中科院分区：
文献类型：
--
作者：
Cohen,DE;Angelico,M;Carey,MC
我们采用准弹性光散射、负染和冷冻断裂电子显微镜研究了新鲜大鼠胆汁中胆汁脂质的时间依赖性物理化学行为。胆汁收集后3 - 5分钟，最早的光散射测量和电子显微镜显示单层囊泡（平均流体动力学半径，Rh = 430-740 A）与混合胶束（Rh = 20-120 A）共存于所有胆汁中。在内源性池引流和牛磺胆酸钠输注期间，胆汁囊泡百分比（1至大于70%）和胶束大小均与胆汁盐浓度（范围1.6-72 mM）呈反比。当胆盐浓度接近或低于估计的临界胶束浓度时，胆囊泡浓度保持恒定或随时间推移略有增加。然而，在胶束胆盐浓度下，囊泡完全转化为胶束的速率与胆盐浓度成正比。作为时间函数的胶束加囊泡的加权Rh平均值的后推法在1 min时给出了约470 A的尺寸，表明在胆汁形成的最早阶段均匀尺寸的单层囊泡占优势。脂质胶束化后，在所有胆汁中均发现囊泡大小的混合蛋白质聚集体。这些实验阐明了胆固醇不饱和胆汁中脂质囊泡和混合胶束的动态共存，并表明胆汁脂质聚集体的囊泡-胶束相互转化是胆汁树内的正常生理现象。（250字处删节）
We employed quasielastic light scattering, negative-stain, and freeze-fracture electron microscopy to study the time-dependent physicochemical behavior of biliary lipids in fresh rat bile. Three to five minutes after bile collection, the earliest light scattering measurements and electron microscopy revealed unilamellar vesicles (mean hydrodynamic radius, Rh = 430-740 A) coexisting with mixed micelles (Rh = 20-120 A) in all biles. Both percent biliary vesicles (1 to greater than 70%) and micellar sizes varied inversely with bile salt concentration (range 1.6-72 mM) both during endogenous pool drainage and sodium taurocholate infusion. With bile salt concentrations in the vicinity of or below the estimated critical micellar concentration, biliary vesicle concentrations remained constant or increased slightly with passage of time. However, with micellar bile salt concentrations, complete conversion of vesicles to micelles occurred at rates that were directly proportional to bile salt concentration. Back-extrapolation of weighted Rh averages of micelles plus vesicles as functions of time gave sizes of approximately 470 A at 1 min, suggesting the predominance of homogeneously sized unilamellar vesicles at the earliest stages of bile formation. After micellization of lipids, mixed protein aggregates of vesicle size were demonstrated in all biles. These experiments elucidate the dynamic coexistence of lipid vesicles and mixed micelles in cholesterol unsaturated biles and demonstrate that vesicle-to-micelle interconversions of biliary lipid aggregates are normal physiological phenomena within the biliary tree.(ABSTRACT TRUNCATED AT 250 WORDS)