Application of Isotopic Techniques Using Constant Specific Activity or Enrichment to the Study of Carbohydrate Metabolism

Tracer techniques have become an establishedpart of metabolic research and indeed are afundamental part of our understanding of carbo-hydrate metabolism in humans. This review is meant to provide a basic overview of the problems and potential pitfalls associated with these techniques in the hope that they are reliably applied to newer areas of research. A quantitative measurement of the substrate fluxes that determine fasting or postprandial glucose concentrations is central to the determination of the pathophysiology of disease states and of measuring the effect of therapeutic interventions on the disease state. During the fasting state, glucose concentrations are dependent on the rate of endogenous glucose production (EGP) relative to the rate of glucose disappearance; measurement using tracer tech-niques is quite straightforward. The situation is more complex in the postprandial state, where gastric emptying