Alterations in transepithelial glucose transport.
Diagram of transepithelial glucose transport under normal conditions (A), hyperglycemia (B), increased tight junction permeability (C) or impaired apical glucose transporter function (D). Gray solid arrows represent glucose uptake capacity across the apical (top) and basolateral (bottom) membranes. Dotted arrows represent transcellular bidirectional fluxes of glucose. Arrow width and font size are modified in each figure according to the primary alteration in glucose transport rate and resulting basolateral and apical concentration, respectively. GLUT-10 is present in the apical membrane and GLUT-1 is present in the basolateral membrane. Intracellular glucose (G) is phosphorylated by hexokinase (HK) for subsequent glycolysis. G6P = glucose-6-phosphate.