Structural and functional analysis of mechanisms of glucose absorption at high maltose concentrations in the rat small intestine in vivo

摘要

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 anisolated segment of the rat small intestine after its perfusion with maltose solutions with both low (25 mM) and high (100 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 afterits 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 disacchande concentrations, and in the range of its superhigh (up to 200 mM) concentrations.