ANIMAL CALORIMETRY THE INFLUENCE OF MORPHINE UPON HEAT PRODUCTION IN THE DOG

1. Two dogs reacted differently to doses of between 12 and 20 mgm. of morphine per kilogram of body weight. 2. Dog XVIII, which remained absolutely quiet in morphine sleep, showed during the second hour after treatment an average fall in the heat production of 11 per cent below the basal level, for the third hour 6 per cent, for the fourth hour 4 per cent. The average reduction for all the periods was 6.2 per cent. The respiratory quotients were unchanged by administration of morphine. 3. In a typical experiment upon this dog the heat production was 0.6 calorie per hour less than the basal value of 16.6 calories, but the animal lost from its body to the calorimeter 6 calories per hour, or 32 per cent, more than it produced. The decrease in heat production cannot therefore be the cause of the fall in body temperature. There was no abnormal condition in the division of heat loss as between radiation and conduction and the evaporation of water. 4. Dog XIX manifested increased irritability with heightened reflexes after administering the drug. The basal metabolism increased by an average of 10 per cent. The maximum increase was 23 per cent after administering morphine, ether and chloroform. The respiratory quotients were higher after giving morphine to this dog, perhaps due to the preference of the active muscle for carbohydrate. 5. The increase in the metabolism of this irritable dog did not prevent a loss of body heat and consequent fall in body temperature after giving morphine. The pathways for the distribution of the heat loss were relatively unaltered. 6. In one experiment when morphine, ether and chloroform were given together there was no change in the body temperature.