Colloid osmotic pressure changes of dog's blood exposed to different mixtures of CO2 and air.
Hansen's membrane manometer method for measuring plasma colloid osmotic pressure was used to obtain the osmolality changes of dogs breathing different levels of CO2. Osmotic pressure was converted to osmolality by calibration of the manometer with saline and plasma, using freezing point depression osmometry. The addition of 10 vol% of CO2 to tonometered blood caused about a 2.0 mosmol/kg H2O increase of osmolality, or 1.2% increase of red blood cell volume. The swelling of the red blood cells was probably due to osmosis caused by Cl- exchanged for the HCO3- which was produced rapidly by carbonic anhydrase present in the red blood cells. The change in colloid osmotic pressure accompanying a change in co2 tension was measured on blood obtained from dogs breathing different CO2 mixtures. It was approximately 0.14 mosmol/kg H2O per Torr Pco2. The corresponding change in red cell volume could not be calculated from this because water can exchange between the plasma and tissues.
D000818:Animals; D002245:Carbon Dioxide; D004285:Dogs; D004911:Erythrocyte Volume; D009994:Osmolar Concentration; D009997:Osmotic Pressure; D010949:Plasma / Q000502:physiology*; D012119:Respiration
D002245:Carbon Dioxide