Insulinotropic action of the pentaacetate esters of D-glucose, D-mannose and D-fructose

The anomers of D-glucose pentaacetate were recently found to stimulate insulin release, without apparently requiring the intervention of a specific carrier system for the transport of the ester across the pancreatic islet B-cell plasma membrane. We have now extended these observations to the pentaacetate esters of D-mannose and D-fructose. Whilst alpha-D-glucose pentaacetate enhanced insulin release from islets deprived of any other exogenous nutrient or incubated in the presence of either D-glucose (4.0 and 7.0 mM) or L-leucine (10.0 mM), alpha-D-mannose pentaacetate (1.7 mM) increased insulin output only from islets incubated in the presence of 7.0 mM D-glucose or 10.0 mM L-leucine. The secretory response to the latter ester remained significantly lower than that evoked by alpha-D-glucose pentaacetate under the same experimental conditions. The beta-anomer of D-fructose pentaacetate failed to affect insulin release significantly whether in the absence or presence of D-glucose or L-leucine. Within the limits of the present study, the insulinotropic action of the pentaacetate esters of monosaccharides thus parallels that of the corresponding unesterified hexoses. (C) 1998 Chapman & Hall Ltd