The Effects of Acute Hypoxia on the Osmotic Pressure of the Plasma

The effect of 20-60 min.periods of acute, severe hypoxia on the osmotic pressure of plasma and on the concentration of several plasma components was observed in thirty-four experiments on adult rabbits, sheep and goats, lambs and fetal sheep and goats.Changes in the pH, 02 and CO2 contents of the blood and in the plasma concentrations of glucose, sodium, potassium, proteins and urea were measured.The osmotic pressure of plasma invariably rose as a consequence of acute, severe hypoxia, from 10 to 45 mOs/kg.H20 above the normal level.In well-fed rabbits 50-100 per cent of the osmotic pressure rise was due to hyperglycemia.In starved rabbits and in the other animals 30-100 per cent of the osmotic pressure rise was due to a rise in concentration of the plasma electrolytes.In one lamb the rise in electrolyte concentration was associated with hypoglycemia.These findings are interpreted as suggesting that severe, acute hypoxia causes in every case a rise of the intracellular osmotic pressure, as a manifestation of a shift from serobic to anaerobic metabolism.The intracellular rise in osmotic pressure would result in a movement of water out of the extracellular fluids and increase their electrolyte concentration.A concomitant rise of the glucose concentration in the extracellular compartment would prevent such a shift of water.