Brasitus T A, Schachter D
Biochemistry. 1982 Apr 27;21(9):2241-6. doi: 10.1021/bi00538a037.
Experiments were performed to test the hypothesis that cholesterol biosynthesis in the rat ileal enterocyte, the major absorptive cell lining the distal epithelium of the small intestine, can modulate the cholesterol content and the motional freedom of the plasma membrane lipids. Decreased sterol biosynthesis in vivo was elicited by feeding sodium taurocholate or by fasting the rats, whereas increased synthesis was induced by biliary ligation or feeding cholestyramine, a bile salt binding resin; these effects were monitored by assay of mucosal 3-hydroxy-3-methylglutaryl coenzyme A reductase. After each procedure, isolated microvillus membranes were examined to determine the lipid composition and the fluorescence anisotropy of 1,6-diphenyl-1,3,5-hexatriene. The results demonstrate that variations in cholesterol biosynthesis in vivo can modulate the cholesterol content and the motional freedom of the lipids of the microvillus membrane; similar effects were not observed on the basolateral membrane. The observations suggest that the normal pattern of decreased lipid motional freedom in microvillus membranes of the distal as compared to the proximal small intestine of the rat results from higher rates of cholesterol biosynthesis in the distal mucosa.
大鼠回肠肠上皮细胞（小肠远端上皮的主要吸收细胞）中的胆固醇生物合成可调节质膜脂质的胆固醇含量和运动自由度。通过喂食牛磺胆酸钠或使大鼠禁食来引发体内固醇生物合成减少，而通过胆管结扎或喂食消胆胺（一种胆汁盐结合树脂）来诱导合成增加；这些效应通过测定黏膜3-羟基-3-甲基戊二酰辅酶A还原酶来监测。在每个程序之后，检查分离的微绒毛膜以确定脂质组成和1,6-二苯基-1,3,5-己三烯的荧光各向异性。结果表明，体内胆固醇生物合成的变化可调节微绒毛膜脂质的胆固醇含量和运动自由度；在基底外侧膜上未观察到类似效应。这些观察结果表明，与大鼠近端小肠相比，远端微绒毛膜中脂质运动自由度降低的正常模式是由于远端黏膜中胆固醇生物合成速率较高所致。
