1986 年 1 巻 1 号 p. 39-51
The effects of fasting and refeeding on the adaptive changes in intestinal sugar absorption was observed by measuring the transmural potential difference (ΔPD) evoked by glucose by infusion of sugars and compared with those in disaccharidase activities, glucose uptake and phlorizin binding activity to the brush border membranes, and morphological parameters.
Rats were fasted for 1, 3, or 5 days. The rats fasted for 5 days were refed for 1 or 3 days further. The ΔPD evoked by glucose, maltose, or sucrose in everted jejunal segments decreased within 1 day of fasting, remained at a same level during fasting, and then increased to the control level after refeeding. Maltase and sucrase activities did not change during the first day of fasting, but did so significantly after 3 days of fasting, in terms of both specific and total activities. On refeeding, disaccharidase activities increased rapidly. However, in spite of significant changes in ΔPDs and disaccharidase activities, glucose uptake by and phlorizin-binding to brush border membrane vesicles from jejunal mucosa did not change in either 5 day-fasted or refed animals compared with the control group. On the other hand, jejunal villus height in rats fasted for 5 days decreased significantly compared with that in control rats and was accompanied by a reduction in epithelial cell height and surface area of villi.
These results suggest that the absorption of sugar in small intestine could adapt to fasting and refeeding with changes in disaccharidase activity and surface area, without any change in glucose carrier.
