The velocity of distribution of sucrose between plasma and interstitial fluid, with reference to the use of sucrose for the measurement or extracellular fluid in man.

The following study had two objectives: first, the examination of the question whether or not sucrose can be substituted for inulin in the measurement of the extracellular fluid in man; and second, the determination of how rapidly equilibrium distribution can be attained. The use of an inulin infusion technique to measure the extracellular fluid in dog and man was initiated by Gaudino, Schwartz and Levitt (1, 2). These investigators used an approximately constant rate of infusion, preceded by a priming infusion, to maintain the plasma concentration of inulin at a constant level for two to 12 hours, during which period it was assumed that uniform concentration throughout the extracellular fluid would be established. After discontinuing the infusion, the total inulin excreted over a period of five hours in the dog or 12 hours in man was determined and, after correction for inulinoid blank in control blood and timed urine samples, the inulin volume of distribution was calculated by dividing total excretion by the plasma concentration at the end of the infusion.23 The authors con-