Effects of D-mannoheptose and D-glycero-D-gulo-heptose upon D-glucose metabolism and insulinotropic action in rat pancreatic islets and D-glucose phosphorylation by hexokinase isoenzymes: comparison with D-mannoheptulose.
The possible use of D-mannoheptose or D-glycero-D-gulo-heptose as substitute of D-mannoheptulose for specific inhibition of D-glucose phosphorylation, metabolism and insulinotropic action was investigated in the present study. The two aldoheptoses failed to duplicate the effect of D-mannoheptulose upon the phosphorylation of D-glucose by yeast hexokinase, bovine heart hexokinase or human B-cell glucokinase. They were poorly phosphorylated by the low-Km hexokinase isoenzymes or liver B-cell glucokinase. D-mannoheptose failed to reproduce the inhibitory action of D-mannoheptulose upon D-glucose metabolism by isolated rat pancreatic islets. Whilst D-glycero-D-gulo-heptose failed to affect glucose-induced insulin release, D-mannoheptose slightly enhanced glucose-induced insulin release when tested at low concentrations (0.75-1.5 mM) and progressively decreased insulin output at higher concentration (3. 0-20.0 mM) in islets exposed to a high (16.7 mM), but not physiological (8.3 mM), concentration of D-glucose. D-mannoheptose, however, also caused a modest inhibition of insulin release evoked by 2-ketoisocaproate. It is concluded, therefore, that neither D-mannoheptose nor D-glycero-D-guloheptose can be considered as suitable substitutes of D-mannoheptulose.
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Document Type: Research Article
Affiliations: Laboratory of Experimental Medicine, Brussels Free University, B-1070 Brussels, Belgium.
Publication date: August 1, 2000
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- The International Journal of Molecular Medicine is a monthly, peer-reviewed journal devoted to the publication of high quality studies related to the molecular mechanisms of human disease. The journal welcomes research on all aspects of molecular and clinical research, ranging from biochemistry to immunology, pathology, genetics, human genomics, microbiology, molecular pathogenesis, molecular cardiology, molecular surgery and molecular psychology.
The International Journal of Molecular Medicine aims to provide an insight for researchers within the community in regard to developing molecular tools and identifying molecular targets for the diagnosis and treatment of a diverse number of human diseases.
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