Thomson A B, Cleland L
Lipids. 1981 Dec;16(12):881-7. doi: 10.1007/BF02534992.
This study was undertaken in vitro to examine the rat jejunal uptake of cholesterol from phospholipid vesicles and from mixed bile salt micelles, under conditions of low effective resistance of the intestinal unstirred water layer. Cholesterol uptake, Jd, occurred from vesicles only when the cholesterol:phospholipid ratio was high. The addition of phospholipid (PL) to micelles comprising 20 mM taurodeoxycholic acid (TDC) extended the concentration of cholesterol, beyond which the relationship between cholesterol concentration and uptake remained linear. When the concentration of cholesterol in the bulk phase was held constant and the concentration of TDC or of PL added to the TDC was increased, there was a decline in cholesterol uptake; this effect was masked when the concentration of TDC was high, or when higher concentrations of PL were added to the mixed micelle. When increasing concentrations of palmitic acid were added to mixed micelles composed of cholesterol, TDC and PL, the uptake of cholesterol decreased; in contrast, cholesterol uptake progressively increased when palmitic acid was added to simple TDC micelles. The results suggest that the mechanism responsible for cholesterol uptake may vary, depending on the nature of the constituents of the micelle, and it is proposed that PL inhibits the intestinal uptake of cholesterol by altering the partitioning of cholesterol out of the micelle.
本研究在体外进行，旨在考察在肠道未搅动水层有效阻力较低的条件下，大鼠空肠从磷脂囊泡和混合胆盐微团中摄取胆固醇的情况。仅当胆固醇与磷脂的比例较高时，才会从囊泡中摄取胆固醇（Jd）。向含有20 mM牛磺脱氧胆酸（TDC）的微团中添加磷脂（PL），可扩大胆固醇的浓度范围，在此浓度范围之外，胆固醇浓度与摄取量之间的关系仍保持线性。当本体相中胆固醇的浓度保持不变，而添加到TDC中的TDC或PL的浓度增加时，胆固醇摄取量会下降；当TDC浓度较高，或向混合微团中添加更高浓度的PL时，这种效应会被掩盖。当向由胆固醇、TDC和PL组成的混合微团中添加浓度不断增加的棕榈酸时，胆固醇摄取量会下降；相反，当向单纯的TDC微团中添加棕榈酸时，胆固醇摄取量会逐渐增加。结果表明，负责胆固醇摄取的机制可能因微团成分的性质而异，并且有人提出PL通过改变胆固醇从微团中的分配来抑制肠道对胆固醇的摄取。
