Relevance of lactate dehydrogenase activity to the control of oxidative glycolysis in pancreatic islet B-cells

Arch Biochem Biophys. 1996 Mar 15;327(2):260-4. doi: 10.1006/abbi.1996.0119.

Abstract

The activities of hexokinase isoenzymes, lactate dehydrogenase, cytosolic NAD-linked glycerophosphate dehydrogenase, mitochondrial FAD-linked glycerophosphate dehydrogenase, and glutamate dehydrogenase were measured in homogenates of rat purified pancreatic B and non-B islet cells. In B cell homogenates, the maximal activity of hexokinase and glucokinase was one to two orders of magnitude lower than that of lactate dehydrogenase. The activity of the mitochondrial FAD-linked glycerophosphate dehydrogenase was also much lower than that of the cytosolic NAD-linked glycerophosphate dehydrogenase . A comparable hierarchy in the activity of these enzymes was observed in non-B islet cells. These findings reinforce the view that the preferential stimulation of oxidative glycolysis observed in insulin-producing cells, when exposed to high concentrations of D-glucose, is attributable to a Ca2+-induced activation of the mitochondrial FAD-linked glycerophosphate dehydrogenase, rather than to saturation of the catalytic activity of lactate dehydrogenase.

Publication types

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

MeSH terms

  • Animals
  • Cell Separation
  • Cytosol / enzymology
  • Glucagon / analysis
  • Glucagon / metabolism
  • Glucokinase / metabolism
  • Glutamate Dehydrogenase / metabolism
  • Glycerolphosphate Dehydrogenase / metabolism
  • Glycolysis*
  • Hexokinase / metabolism*
  • Insulin / analysis
  • Insulin / metabolism
  • Islets of Langerhans / cytology*
  • Islets of Langerhans / metabolism*
  • Isoenzymes / metabolism
  • Kinetics
  • L-Lactate Dehydrogenase / metabolism*
  • Mitochondria / enzymology
  • Oxidation-Reduction
  • Rats

Substances

  • Insulin
  • Isoenzymes
  • Glucagon
  • Glycerolphosphate Dehydrogenase
  • L-Lactate Dehydrogenase
  • Glutamate Dehydrogenase
  • Hexokinase
  • Glucokinase