Uptake of Radioactive D-Glucose Anomers by Pancreatic Islets

Isolated rat islets were incubated in media containing either the a or /3 anomer of D-[l-3H]glucose for 5 min at 37°. The amounts of the two anomers incorporated were determined using L-[l-14C]glucose as an extracellular space marker. The incor-poration of /3-D-glucose was about twice that of a-D-glucose. Our previous and present results suggest that the two anomers of D-glucose each have a preferential function in pancreatic beta cells; a-D-glucose stimulates insulin secretion, and £-D-glucose is transported into the cells. In water, D-glucose equilibrates among three structures (1, 2): a anomer, /! anomer, and a so-called aldehyde form, as shown in the following equation. a anomer;= ± aldehyde form ^ ^ £ anomer (36.5%) (0.003%) (63.5%) Almost the same equilibration of D-glucose is observed in blood (3). However, th