Isomeric and anomeric specificity of the metabolic and secretory response of rat pancreatic islets to glucose pentaacetate

In the presence of 2.8 mM D-glucose, beta-D-glucose pentaacetate (1.7 mM) a ugmented insulin release from isolated rat pancreatic islets more than alph a-D-glucose pentaacetate. Likewise, the further increment in insulin output evoked by nateglinide (0.01 mM) was higher in islets exposed to beta- rath er than alpha-D-glucose pentaacetate. Inversely, in the presence of 2.8 mM unesterified D-glucose, alpha-L-glucose pentaacetate, but not beta-L-glucos e pentaacetate, significantly augmented insulin output. The higher insulino tropic potency of the beta-anomer of D-glucose pentaacetate coincided with the fact that it significantly increased the paired ratio between D-[U-C-14 ] glucose oxidation and D-[5-H-3]glucose utilization, whereas alpha-D-gluco se pentaacetate failed to do so. These findings are interpreted to support the concept that the stimulation of insulin release by these eaters is larg ely attributable to their direct interaction with a stereospecific receptor , with preference for the configuration of the C-1 common to beta-D-glucose pentaacetate and alpha-L-glucose pentaacetate.