Energy and electrolyte metabolism and adrenal responses during work in dogs

¹ Quartermaster Food and Container Institute for the Armed Forces, U. S. Army Quartermaster Research and Engineering Command, Chicago, Illinois

Studies with dogs were undertaken to determine whether nitrogen metabolism during aerobic treadmill running is affected by recency of food intake. Over a 6-hr period after intake of a standard meal, the percentage of energy derived from carbohydrate, fat, and protein oxidation was relatively constant at 70, 24, and 6, respectively. With postabsorptive dogs, the percentages of energy derived from carbohydrate, fat, and protein were significantly different (P < .01) and in the ratio of 45:53:2. Urinary nitrogen, amino acids, 17-hydroxycorticosteroids, Na, and K were examined in postabsorptive animals at rest and at work. Over a 3-hr period, the urinary NPN and Na were 0.49 g and 5.8 mEq, respectively, and unaffected by work; K and hydroxycorticosteroids were 4.6 mEq and 228 µg, respectively, and significantly elevated during work. Of 18 amino acids measured, only cystathionine excretion was significantly altered during work. In running trials of 88–600 min duration, both NPN and 17-hydroxycorticosteroids showed a tendency to increase with calorie expenditure.