Effects of dehydration on plasma water and extracellular fluid volumes in the rat.

Dehydration was induced in rats by depositing 3 ml of hyperosmolar glucose (1670 mOsm/kg) in a closed small bowel loop. The plasma water and extracellular fluid volumes of the whole animal and selected tissues were subsequently studied with 125I human serum albumin and 51Cr EDTA. The fluid accumulation in the bowel was equivalent to 122% of the plasma water volume. The plasma water volume of the whole animal was significantly reduced by 31%, while the extracellular fluid volume reduction by 8% was not statistically significant. The regional extracellular fluid volumes decreased in the lung (9%), the liver (34%), the gastric antrum (15%) and the omental fat (24%). The results show regional differences in tissue response to dehydration.