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Active transport of myo-inositol and its relation to the sugar transport system in hamster small intestine

1970; Elsevier BV; Volume: 203; Issue: 2 Linguagem: Inglês

10.1016/0005-2736(70)90145-8

1879-2642

Wolfgang F. Caspary, Robert K. Crane,

Diabetes Treatment and Management

Incubation in vitro of segments of hamster small intestine has been used to study the mode of absorption of myo-inositol. By all current criteria, myo-inositol is actively transported. We have observed accumulation against a concentration gradient, energy-dependence, Na+-dependence, phlorizin sensitivity, and saturation kinetics with a Km of 0.14 mM. Sugars which interact with and undergo the translocation step of glucose transport are non-competitive inhibitors of the transport of myo-inositol. myo-Inositol has no effect on the d-glucose transport system. Phlorizin interacts competitively with the myo-inositol binding site with an affinity 10–100-fold less than it has for the common sugar binding site. These results indicate that the pathway for myo-inositol to cross the brush border membrane is not entirely the same as the d-glucose pathway. However, they also indicate that there is an interaction between the two at the level of translocation.