Lipid composition and membrane fluidity of monkey small intestinal brush border membrane: regional differences.

Brush border membrane vesicles (BBMV) isolated from various regions of monkey small intestine were compared for lipid composition, membrane fluidity and sodium-dependent D-glucose transport. Total phospholipid content was same in all regions whereas cholesterol content was high in duodenum and jejunum as compared to ileum resulting in higher cholesterol/phospholipid molar ratios. Regional differences in individual phospholipid subclasses and fatty acids in total lipids were also observed. Fluidity measurements showed that the membranes of duodenum and jejunum were less fluid than ileum. The change in BBMV fluidity appears to be due to alteration in cholesterol/phospholipid ratio and phospholipid composition. The sodium dependent D-glucose uptake was more in duodenum and jejunum as compared to ileum. These results suggest that there is a regional difference in the lipid composition and fluidity of BBMV in monkey small intestine which may influence their function.