Meeting Abstract

P1.88  Monday, Jan. 4  D-glucose and D-fructose transport across lobster intestine OBI, Ijeoma/ E*; AHEARN, Greg/ A; University of North Florida; University of North Florida i.obi@unf.edu

Dietary sugars are the main source of energy in many living organisms, and they play an essential role in the proper functioning of organs. The mechanisms of transepithelial absorption of dietary D-glucose and D-fructose in crustaceans have not been extensively studied and therefore were examined using the intestine of the lobster, “”Homarus americanus”, in the present investigation. Lobster intestines were isolated and mounted in a perfusion chamber to determine the mucosal to serosal (MS) mechanisms of “^”3””H-D-glucose and “^”3””H-D-fructose transport across the apical membrane. The results indicated that “^”3””H-D-glucose transport was dependent on sodium and was carrier mediated. Furthermore, “^”3””H-D-glucose transport was inhibited by phloridzin, but was neither inhibited by phloretin nor cytochalasin B. In contrast, “^”3””H-D-fructose transport was carrier mediated, but there was no difference in the rate of “^”3””H-D-fructose uptake in the presence or absence of sodium. In addition, “^”3””H-D-fructose transport was not inhibited by phloridzin, phloretin or cytochalasin B. Taken together, these results suggest that on the apical membrane of the lobster intestine, (1) an SGLT1-like transport protein may be responsible for transepithelial D-glucose uptake; (2) transepithelial D-fructose transport may occur through a separate transport protein independent of sodium; and (3) a GLUT2-like carrier protein may not be involved in transpithelial transport of either sugar. The proposed mechanisms of transepithelial transport of D-glucose and D-fructose across the lobster intestinal epithelium from lumen to blood are similar to the standard models proposed for D-glucose and D-fructose uptake in mammalian intestine. Supported by NSF Grant number: IBN 04-21986.