Measurement of Extracellular Fluid Volume of Nephrectomized Dogs With Mannitol, Sucrose, Thiosulfate and Radiosulfate

¹ From the Department of Physiology, Cornell University Medical College, New York City

Volumes of distribution of mannitol, sucrose, thiosulfate and radiosulfate have been measured simultaneously in nephrectomized dogs. The volume of distribution of each substance is reproducible when the substance is reinfused 6 hours later. There appears to be no increase in the extracellular fluid volume during this interval as a result of the nephrectomy. The logarithm of the concentration of mannitol, sucrose and radiosulfate continues as a simple exponential function of time from the 3rd to 30th hour after their infusion. The volumes of distribution of mannitol and radiosulfate reflect increments in extracellular fluid with fair accuracy, while the sucrose distribution measures only 72% of a 1-liter expansion of extracellular fluid. There are serious limitations in the application of thiosulfate distribution to such measurements.

Note:
with the technical assistance of Angela Plinke and Herman Sharma