GLUCOSE KINETICS IN INTERSTITIAL FLUID CAN PREDICTED BY COMPARTMENTALMODELING

The purposes of this study were to define in sheep a compartmental mod el for glucose kinetics in the basal condition and to test the hypothe sis that interstitial fluid obtained by sampling thoracic duct lymph ( TDL) represents one or more peripheral compartments of the glucose mod el. A bolus of [6,6-H-2]glucose was injected in nine animals, followed by frequent sampling of blood and TDL. Linear kinetic modeling has be en applied to plasma data, indicating that a three-compartment model a dequately describes glucose kinetics. Both catenary and mammillary mod els were identified, and their predictions for the tracer behavior in nonaccessible pools were evaluated. In all experiments, regardless of the model structure, predictions in the compartment most rapidly excha nging with blood (pool 2) well matched the measured tracer-to-tracee r atio in TDL. Furthermore, modeling analysis showed that 90-95% of the tracer in TDL comes from this pool. This supported the physiological i dentification of a peripheral pool of glucose kinetics as extracellula r fluid represented by TDL measurements.