Plasma and erythrocyte Na, K, Cl and water in hypothermic and hyperthermic dogs

¹ Clinical Physiology Laboratories, Institute of Clinical Investigation, University of Tennessee College of Medicine, Memphis, Tennessee

Plasma and erythrocyte Na, K, Cl and water have been determined in hyperventilated dogs cooled to 25°C for periods up to 4 hours, in animals heated to either 41.5°C or 42.5°C for 1 hour and in hyperventilated-normothermic dogs. The induced respiratory alkalemia in both normothermic and hypothermic animals appeared to result in a shift of Na from plasma into red cells. Plasma K was reduced in both normothermic and hypothermic dogs, whereas a K elevation in erythrocytes occurred only in the normothermic animals following hyperventilation. Erythrocyte K remained unchanged in hypothermia. It seems, therefore, that the fall in plasma K which occurs in alkalemic normothermic dogs is due partially to a movement of K into red cells whereas, in hypothermia the K leaving extracellular fluid enters cells other than erythrocytes. The plasma and red cell electrolyte changes observed in the two hyperthermic groups of dogs were all in the direction of an increase. It is concluded that these changes were primarily the result of the increased body temperature and of consequent reductions in plasma and red cell water content, rather than the result of the blood pH changes associated with hyperthermia.