TWENTY YEARS AGO, Ugolev et al. (15) noted that “under physiological conditions [the] two systems of glucose transport, Na -dependent and Na -independent, function. The first one is less potent but more resistant to experimental influences.” This statement sums up fairly accurately what has happened in the field of intestinal sugar absorption in the last six years as exemplified by increases in...

GLUT2-/- mice reexpressing GLUT1 or GLUT2 in their beta-cells (RIPGLUT1 x GLUT2-/- or RIPGLUT2 x GLUT2-/- mice) have nearly normal glucose-stimulated insulin secretion but show high glucagonemia in the fed state. Because this suggested impaired control of glucagon secretion, we set out to directly evaluate the control of glucagonemia by variations in blood glucose concentrations. Using fasted R...

The pancreatic B-cell GLUT2 transporter and glucose metabolism were examined in isolated rat islets subjected to treatments affecting insulin secretion. Diazoxide was used to inhibit, while glipizide or depolarization of the plasma membrane with a high extracellular K(+) concentration were used to stimulate insulin release in short-term experiments. Islet GLUT2 and insulin were determined by qu...

Nonobese diabetic (NOD) mice are susceptible strains for Type 1 diabetes development, and Nonobese Diabetes-Resistant (NOR) mice are defined as suitable controls for NOD mice in non-MHC-related research. Diabetes is often accelerated in NOD mice via Streptozotocin (STZ). STZ is taken inside cells via GLUT2 transmembrane carrier proteins, the major glucose transporter isoforms in pancreatic beta...

Glucose transporters (GLUTs) have been implicated in the survival of various physiological stresses in mammals; however, little is known about the role of these proteins in stress tolerance in lower vertebrates. The wood frog (Rana sylvatica), which survives multiple winter-related stresses by copiously mobilizing hepatic glycogen stores, is an interesting subject for the study of glucose trans...

OBJECTIVES A physiological adaptation to a sugar-rich meal is achieved by increased sugar uptake to match dietary load, resulting from a rapid transient translocation of the fructose/glucose GLUT2 transporter to the brush border membrane (BBM) of enterocytes. The aim of this study was to define the contributors and physiological mechanisms controlling intestinal sugar absorption, focusing on th...

The biosynthesis, intracellular transport, and surface expression of the beta cell glucose transporter GLUT2 was investigated in isolated islets and insulinoma cells. Using a trypsin sensitivity assay to measure cell surface expression, we determined that: (a) greater than 95% of GLUT2 was expressed on the plasma membrane; (b) GLUT2 did not recycle in intracellular vesicles; and (c) after tryps...

Glucose production by the liver is a major physiological function, required to prevent the development of hypoglycemia in postprandial and fasted states. Hepatic glucose metabolism is highly regulated not only by changes in plasma insulin and glucagon levels, but also by changes in blood glucose concentrations. In the fasted state, a decrease in glycemia reduces the intracellular levels of gluc...