Intestinal metabolism and transport of alpha-disaccharide conjugates: the role of disaccharidase in the Na+/glucose cotransporter-mediated transport.

摘要

Intestinal transport and metabolism of p-nitrophenyl alpha-disaccharides were studied. In the absorption of p-nitrophenyl alpha-melibioside, no compounds other than p-nitrophenyl alpha-melibioside were detected on either the mucosal or the serosal side. In the absorption of p-nitrophenyl alpha-maltoside, on the other hand, p-nitrophenyl alpha-glucoside was formed on the mucosal side to appear on the serosal side. p-Nitrophenol and p-nitrophenyl beta-glucuronide also appeared on the serosal side in the absorption of p-nitrophenyl alpha-maltoside, and the total amount transported to the serosal side was significantly decreased in the absence of Na+ (a cosubstrate of Na+/glucose cotransporter (SGLT1)). Furthermore, the total transport clearance of p-nitrophenyl alpha-glucoside formed from p-nitrophenyl alpha-maltoside on the mucosal side in the p-nitrophenyl alpha-maltoside absorption, was similar to that of the absorption of p-nitrophenyl alpha-glucoside itself. These results led to the conclusion that the intestinal absorption of disaccharide conjugate depended on disaccharidase, and the absorption of the alpha-maltose conjugate occurred sequentially by the maltase-catalyzed hydrolysis of the disaccharide conjugate and SGLT1-mediated transport of the glucose conjugate.