Interaction of phlorizin and phloretin with glucose transport system of the pigeon intestine
Patil, S.D.; Prakash, K.; Hegde, S.N.
Indian Journal of Biochemistry and Biophysics 23(4): 208-211
1986
ISSN/ISBN: 0301-1208 PMID: 3570337 Document Number: 271553
Interaction of phlorizin and phloretin with in vitro transport of D-[U-14C]glucose in the pigeon small intestine has been investigated. Phlorizin readily inhibits D-glucose uptake in the presence (not absence) of Na+ ions as well as in the presence and absence of Na+ gradient. In contrast, phloretin has no immediate effect on glucose uptake both in the presence and absence of Na+ ion as well as in the presence and absence of Na+ gradient. However, it enhances the equilibrium level of glucose binding to mucosal tissue by two-fold and affects the sugar uptake only when tissues are preincubated with it. The kinetic analysis of phlorizin/phloretin interference with glucose transport yields parallel lines. The calculated inhibitory constant (Ki) values are 5.5 .mu.mole and 0.28 mM respectively for phlorizin and phloretin. It is possible that (i) phlorizin and phloretin mutually compete for available binding sites on the glucose transporter of brush border membrane and (ii) a phenol binding site is involved in the normal maintenance of glucose transport rate.