Glucose oxidation and contents of free amino acids in pancreatic β-cells stimulated by a non-metabolizable leucine analogue

Abstract Oxidation of glucose and the contents of free amino acids were measured in β-cell-rich pancreatic islets exposed to stereoisomers of the non-metabolizable leucine analogue 2-aminobicyclo(2,2,1)heptane-2-carboxylic acid. The insulin-releasing isomer b(−) appeared to stimulate glucose oxidation, whereas the inactive b(+) form was without effect. 2-aminobicyclo(2,2,1)heptane-2-carboxylic acid reduced the islet contents of aspartic acid, γ-aminobutyric acid and glutamic acid and increased that of phenylalanine. Since the two isomers of 2-aminobicyclo(2,2,1)heptane-2-carboxylic acid did not differ in their ability to alter the intracellular contents of free amino acids, these alterations are probably not significant for the regulation of insulin release. It could not be excluded that increased glucose metabolism may contribute to the stimulation of insulin release by the b(−) isomer of 2-aminobicyclo(2,2,1)heptane-2-carboxylic acid.