Body fluid compartments in rabbits on exposure to acute hypobaric hypoxia

Body fluid compartments were studied in rabbits divided into three groups--control, exposed to acute hypoxia, and exposed to hypoxia after treatment with 2 mg frusemide intramuscularly. Total body water, extracellular body water, and plasma space were determined using the triple radiotracer technique. Total body water decreased insignificantly with no change in extracellular body space on exposure to hypoxia. Plasma volume and blood volume showed a significant decrease with a significant increase in haematocrit. In rabbits pretreated with frusemide, total body water, extracellular body water, plasma volume, blood volume, and interstitial fluid space decreased significantly on hypoxic exposure. This study suggested hypohydration on acute hypoxic exposure with a loss of intracellular water, while pretreatment with frusemide resulted in further hypohydration with a loss from both intracellular and extracellular compartments. The results have been discussed in relation to suggested use of diuretics on induction to high altitude.