Groen A K, Goldhoorn B G, Egbers P H, Chamuleau R A, Tytgat G N, Bovée W M
Department of Gastroenterology and Hepatology, Academic Medical Center, Amsterdam, The Netherlands.
J Lipid Res. 1990 Jul;31(7):1315-21.
Biliary cholesterol/phospholipid vesicles play an important role in the pathogenesis of gallstone disease. A prerequisite for the study of the lipid composition and stability of these vesicles is a reliable method to quantify the amount of vesicular lipid. In the present report we show that NMR can be used to determine the distribution of biliary lecithin between the micellar and vesicular phases. The relatively large size of the vesicles leads to such a broadening of the lipid resonances that they are no longer visible in high resolution 1H-NMR spectra. Since micelles are much smaller, lipid present in the micellar phase does give rise to sharp peaks in 1H-NMR spectra. Micellar lecithin can easily be quantified in these spectra. The resonances of cholesterol are masked by the closely related bile acid that is present in a much higher concentration. By determining the difference between chemically and NMR estimated lecithin, the distribution of this phospholipid between the micellar phase and vesicular phase can be assessed. We have compared the results of NMR with gel permeation and density gradient ultracentrifugation. Using standard fractionation conditions, both gel permeation and density gradient ultracentrifugation lead to an underestimation of vesicular lecithin, the difference being minor at relatively high total lipid concentrations (10 g/dl) but large in diluted model bile. We conclude that 1H-NMR can be used to determine the distribution of lecithin in model bile.(ABSTRACT TRUNCATED AT 250 WORDS)
胆汁胆固醇/磷脂囊泡在胆结石病的发病机制中起重要作用。研究这些囊泡的脂质组成和稳定性的一个前提是要有一种可靠的方法来定量囊泡脂质的含量。在本报告中，我们表明核磁共振（NMR）可用于确定胆汁卵磷脂在胶束相和囊泡相之间的分布。囊泡相对较大的尺寸导致脂质共振峰变宽，以至于在高分辨率的1H-NMR谱中不再可见。由于胶束要小得多，胶束相中存在的脂质在1H-NMR谱中确实会产生尖锐的峰。胶束卵磷脂很容易在这些谱中定量。胆固醇的共振峰被浓度高得多的密切相关的胆汁酸所掩盖。通过确定化学法和NMR法估算的卵磷脂之间的差异，可以评估这种磷脂在胶束相和囊泡相之间的分布。我们将NMR的结果与凝胶渗透法和密度梯度超速离心法进行了比较。在标准分级分离条件下，凝胶渗透法和密度梯度超速离心法都会导致对囊泡卵磷脂的低估，在总脂质浓度相对较高（10 g/dl）时差异较小，但在稀释的模型胆汁中差异较大。我们得出结论，1H-NMR可用于确定模型胆汁中卵磷脂的分布。（摘要截短于250字）
