Differences in the time course of the metabolic response of B and non-B pancreatic islet cells to D-glucose and metabolized or non-metabolized hexose esters

Biochem Biophys Res Commun. 1999 Aug 27;262(2):346-9. doi: 10.1006/bbrc.1999.1219.

Abstract

The early (min </= 1) and late (min 45) changes in NAD(P)H fluorescence caused by alpha-D-glucose pentaacetate, beta-L-glucose pentaacetate, and beta-D-galactose pentaacetate (1.7 mM each), alone or together with either L-leucine (10.0 mM) or D-glucose (8.3 mM), were monitored in purified pancreatic B and non-B rat islet cells. Whilst D-glucose caused a rapid increase in the NAD(P)H signal in B-cells, but not so in non-B cells, alpha-D-glucose pentaacetate, but not the two other monosaccharide esters, rapidly augmented the NAD(P)H signal in both B and non-B cells. After 45 min, the NAD(P)H signal was increased by either D-glucose in both B and non-B islet cells or alpha-D-glucose pentaacetate. At this late time, beta-L-glucose pentaacetate also increased the NAD(P)H signal in B cells exposed to L-leucine. These findings emphasize the relevance of differences in the time course of D-glucose uptake by B and non-B islet cells as a determinant of rapid changes in redox state. They also provide further support for the role of intracellular Ca(2+) regulating the activity of key Ca(2+)-responsive mitochondrial dehydrogenases. Last, they reinforce the view that the effects of hexose pentaacetates upon insulin and glucagon release entail a dual modality, linked either to the catabolism of their hexose moiety or to a direct effect of the esters themselves upon a stereospecific receptor system.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium / metabolism
  • Cell Separation
  • Esters / pharmacology
  • Galactose / analogs & derivatives*
  • Galactose / pharmacology
  • Glucose / analogs & derivatives*
  • Glucose / pharmacology
  • Islets of Langerhans / cytology*
  • Islets of Langerhans / drug effects*
  • Mitochondria / enzymology
  • NAD / metabolism
  • NADP / metabolism
  • Rats
  • Stereoisomerism

Substances

  • Esters
  • NAD
  • glucose pentaacetate
  • NADP
  • galactose peracetate
  • Glucose
  • Calcium
  • Galactose