Metabolism and disorders of the endocrine pancreas.

The release of insulin evoked by D-glucose and other nutrient secretagogues in the pancreatic B-cell is causally linked to an increase in ATP generation rate. This fuel concept is documented by the higher glycolytic and secretory responses evoked by the alpha-anomer, as distinct from beta-anomer, of either D-glucose or D-mannose. Experimental models of B-cell dysfunction are characterized by several site-specific anomalies in hexose metabolism. For instance, alpha-stereospecificity of the functional response is apparently perturbed in spontaneously diabetic rats or human subjects. Because phosphoglucoisomerase participates in the anomeric specificity of D-glucose metabolism, the intrinsic properties of this enzyme are reevaluated, with emphasis on both the anomeric specificity and discrimination towards hydrogen isotopes as assessed by magnetic resonance imaging.