UBC Theses and Dissertations
Lactate and pyruvate metabolism during hyperthermia in the dog Dunn, Robert Bruce
The effects of an increase in body temperature per se on the lactate and pyruvate concentrations of the arterial blood, muscle venous blood, sagittal sinus blood, and cerebrospinal fluid were determined. Paralysed anesthetized dogs with near normal arterial pH and PC0(2) values were ventilated with a 50% 0(2), 50% N(2) mixture and heated to a temperature of 42°C and maintained at this temperature for a period of 2 hours. During hyperthermia a slight increase in lactate and pyruvate was observed in the arterial blood. However, this was not statistically significant. Also a slight increase in the concentration of these substances occurred in the muscle venous blood and sagittal sinus blood. This change, however, was parallel to that observed in the arterial blood. The lactate-pyruvate ratio of the arterial blood, muscle venous blood and sagittal sinus blood did not show any significant change and thus no increase in anaerobic processes was detected during the hyperthermic period. On the other hand the cerebrospinal fluid lactate and pyruvate increased significantly throughout the hyperthermic period but maintained a constant lactate-pyruvate ratio. The results indicate that the increase of lactate and pyruvate in the cerebrospinal fluid are a result of an increased rate of aerobic glycolysis. The fact that the increases observed in the cerebrospinal fluid lactate and pyruvate were not reflected in the cerebral venous blood indicates lactate and pyruvate may have difficulty in diffusing across the blood brain barrier and cerebral venous blood is thus a poor index of cerebral lactate and pyruvate changes.
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