Sugar absorption and secretion by winter flounder intestine.
Transport of sugars by winter flounder (Pseudopleuronectes americanus) intestine has been examined, and the following observations have been made. 1) No net absorption of D-galactose was found in controls; however, mucosally applied 0.1 mM phlorizin stimulated the mucosal-serosal flux with net sugar secretion. 2) Net absorption of methyl glycosides was inhibited by D-galactose, 0.1 mM ouabain, and phlorizin (without induction of secretion). 3) Net secretion of 2-deoxy-D-galactose was found without cellular accumulation of free sugar. The secretory process had a Km of 10 mM and was inhibited by serosally applied 0.1 mM phloretin, bilateral replacement of Ringer Na+ by choline, serosal ouabain, and D-galactose. 4) No net absorption or secretion of 2-deoxy-D-glucose was found with a variety of experimental conditions. 5) At least two active transport systems for sugars appear to be operative in the flounder intestine: a conventional Na+-dependent sugar transport system across the brush border that allows net absorption and a Na+-dependent secretory system that apparently also operates across the mucosal border. Because D-galactose is transported by both systems, there is no net flux of this sugar. Several possible models for the net secretory system are discussed.
D000818:Animals; D050260:Carbohydrate Metabolism; D003847:Deoxyglucose / Q000378:metabolism; D005399:Fishes / Q000378:metabolism*; D005643:Fucose / Q000378:metabolism; D005690:Galactose / Q000378:metabolism; D006571:Heterocyclic Compounds / Q000494:pharmacology; D007097:Imines / Q000494:pharmacology; D066298:In Vitro Techniques; D007408:Intestinal Absorption; D007413:Intestinal Mucosa / Q000378:metabolism*; D007424:Intracellular Fluid / Q000378:metabolism; D008759:Methylglycosides / Q000378:metabolism; D010042:Ouabain / Q000494:pharmacology; D010693:Phloretin / Q000494:pharmacology; D010695:Phlorhizin / Q000494:pharmacology; D012964:Sodium / Q000502:physiology
D006571:Heterocyclic Compounds; D007097:Imines; D008759:Methylglycosides; D005643:Fucose; D010042:Ouabain; C014925:RMI 12330A; D003847:Deoxyglucose; D012964:Sodium; D010695:Phlorhizin; D010693:Phloretin; D005690:Galactose