The effects of the production of sodium depletion by peritoneal dialysis with 5 percent glucose on the volume and composition of the extracellular fluid of dogs.

1. The volumes and compositions of the extracellular and peritoneal fluids were monitored in functionally nephrectomized dogs during a period of 4 hr of peritoneal dialysis with 5% glucose.2. The extracellular fluid volume ([(14)C]mannitol space), sodium, potassium and chloride concentrations decreased, while the peritoneal fluid volume, sodium, potassium and chloride concentrations increased.3. Movement of water from the e.c.f. to non-extracellular sites occurred, reaching a maximum after 1 hr; thereafter, the movement of water was first reduced, and later reversed.4. From the volumes and compositions of the extracellular and peritoneal fluids, the total contents of solutes in the two compartments were calculated.5. There was a mobilization of sodium and chloride from non-extra-cellular sites, which became significant after 2 hr of dialysis, and increased throughout the remainder of the period of dialysis.6. The physiological significance of these changes is discussed.