Transport of 3-O-methyl-D-glucose into mammalian pancreatic -cells.

Abstract

The transport and oxidation of 3-O-methyl-d-(U-14C)glucose was studied in microdissected pancreatic islets of obese-hyperglycemic mice. There was no significant production of14CO2 during incubation for 2 h. A comparison with the uptake of sucrose and mannitol indicated that 3-O-methyl-d-glucose was uniformly distributed across the β-cell plasma membrane. Externald-glucose inhibited the entry of 3-O-methyl-d-glucose and caused a significant net loss of 3-O-methyl-d-glucose from islets equilibrated with this compound. The transport of 3-O-methyl-D-glucose was also markedly reduced in the presence of phlorizin or phloretin, whereasd-mannoheptulose ord-glucosamine exerted a slight inhibition. The results support our hypothesis that the transport ofd-glucose into the pancreatic β-cells is carriermediated, and indicate that 3-O-methyl-d-glucose is a non-metabolizable substrate for this carrier in the pancreatic islets. Since in contrast tod-glucose 3-O-methyl-d-glucose does not stimulte insulin release from the type of islets used, the secretagoric recognition system ford-glucose is probably not identical with the membrane transport system.