Garriga C, Vázquez C M, Ruiz-Gutiérrez V, Planas J M
Department de Fisiologia-Divisió IV, Facultat de Farmàcia, Universitat de Barcelona, Spain.
Poult Sci. 2002 Apr;81(4):537-45. doi: 10.1093/ps/81.4.537.
Na+-dependent D-glucose transport was studied in brush-border membrane vesicles from duodenum, jejunum, and ileum of 5- to 6-wk-old chickens. Regional differences were found, and both initial rates and accumulation ratio of D-glucose were higher in the proximal part of the small intestine than in the ileum. To establish the mechanism(s) underlying these differences we have studied the density of Na+-dependent D-glucose cotransporter (SGLT1) as well as lipid composition and fluidity. Phlorizin-specific binding and Western blot analysis indicated a decrease in the amount of SGLT1 in the ileum when compared to the duodenum and jejunum. The distal part of the small intestine also showed a decrease in free cholesterol content and saturated-to-unsaturated fatty acid ratio together with an increase in lipid content and phosphatidylcholine-to-sphingomyelin ratio. These results were associated with a decrease in the diphenylhextriene fluorescence polarization found in brush-border membranes of the ileum. We can conclude that the decrease in the apical D-glucose transport found in the ileum is primarily due to a reduction in the amount of SGLT1 present in the brush-border membrane rather than the differences in the lipid composition and fluidity.
对5至6周龄鸡的十二指肠、空肠和回肠的刷状缘膜囊泡中的钠依赖性D-葡萄糖转运进行了研究。发现存在区域差异，小肠近端的D-葡萄糖初始速率和积累率均高于回肠。为了确定这些差异背后的机制，我们研究了钠依赖性D-葡萄糖共转运蛋白（SGLT1）的密度以及脂质组成和流动性。根皮苷特异性结合和蛋白质印迹分析表明，与十二指肠和空肠相比，回肠中SGLT1的量减少。小肠远端还显示游离胆固醇含量和饱和脂肪酸与不饱和脂肪酸的比例降低，同时脂质含量和磷脂酰胆碱与鞘磷脂的比例增加。这些结果与回肠刷状缘膜中发现的二苯基己三烯荧光偏振降低有关。我们可以得出结论，回肠中顶端D-葡萄糖转运的减少主要是由于刷状缘膜中SGLT1量的减少，而不是脂质组成和流动性的差异。
