Digestion and Absorption of Sugars and Sugar Substitutes in Rat Small Intestine

Abstract

The bioavailability of newly developed sugar substitutes was observed by measuring the transmural potential difference (ΔPD) evoked by Na+-dependent active trasport of glucose, which is supposed to be produced by the hydrolysis of sugar substitutes. ΔPD was measured using everted intestinal sac prepared from jejunum of adult rats and compared with the digestibility of sugar substitutes in the mucosal homogenate of everted sac. ΔPDs evoked by glucose, maltose or maltosylfructose had almost the same levels, however, the ΔPD evoked by sucrose was a little lower. ΔPDs evoked by maltitol or palatinose were low, and ΔPDs evoked by fructooligosaccharides were negligible. The hydrolyzing activities of these sugars and sugar substitutes by the mucosal homogenate were correlated with the ΔPDs. A significant positive correlation was observed between ΔPDmax of various sugars and sugar substitutes and the Vmax of their corresponding hydrolyzing activities. Also, a significant positive correlation was observed between Kt and Km values of these sugars. These results suggest that the absorption of sugar substitutes is dependent on digestibility by membrane digestive enzymes. © 1986, Center for Academic Publications Japan. All rights reserved.