Role of Glucose as a Regulator and Precursor of Amino Acids in the Pancreatic β-Cells

A microchromatographic technique was employed for studying the role of glucose as a regulator and precursor of amino acids in β-cellrich pancreatic islets microdissected from obesehyperglycemic mice. After incubation with 5 HIM D-(U-14C)-glucose, most amino acid radioactivity was found in aspartic acid, γ-aminobutyric acid (GABA) and glutamic acid. There was an enhanced incorporation of glucose carbon into glutamic acid when the glucose concentration was raised to 20 IHM. The high glucose concentration tended to reduce the size of the amino acid pool and was also associated with increased incorporation of radioactivity per mole of aspartic acid, glutamic acid and GABA. The specific incorporation into GABA was 2–4 times higher than into glutamic acid, suggesting intracellular compartmentation of the latter amino acid. No significant changes occurred in the islet concentrations of individual amino acids or in their formation from glucose after addition of the insulin secretagogue glibenclamide or after inhi...