STRUCTURAL AND FUNCTIONAL ANALYSIS OF MECHANISMS OF GLUCOSE ABSORPTION AT HIGH
MALTOSE CONCENTRATIONS IN THE RAT SMALL INTESTINE IN VIVO
Ya. Yu. Komissarchik,1 E. S. Snigirevskaya,1 N. M. Grefner,1
L. V. Kever,1 A. A. Gruzdkov,2 L. V. Gromova 2
1 Institute of Cytology, RAS, and 2 the I. P. Pavlov Institute of Physiology RAS,
St. Petersburg
To elucidate the mechanism of glucose absorption at high substrate concentations, we studied structural and
ultrastructural peculiarities of enterocytes arranged at different levels along the intestinal villus. The
preparations wereo btained from an isolated segment of the rat small intestine after its perfusion with maltose
solutions with both low (25 mM) and high (l100 mM) concentrations, respectively. Under conditions of chronic
experiment at high substrate concentration, an enlargement of intercellular clefts, indicating glucose absorption,
occurred in deeper areas of the villus. Besides, also in chronic experiment, we studied kinetics of maltose
hydrolysis and derived glucose absorption in the isolated segment of the rat small intestine after its perfusion
with maltose at superhigh (up to 200 mM) initial concentrations. Based on these data, a conclusion is made that
active transport is the main mechanism of absorption of glucose derived from maltose hydrolysis, operating both at
low disaccharide concentrations, and in the range of its superhigh (up to 200 mM) concentrations.
Key words: small intestine, membrane digestion, glucose absorption, maltose hydrolysis, electron
microscopy, immunocytochemical analysis
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