Mechanism of the Specific Dynamic Action of Ingested Protein

• Published in: Proceedings of the Symposium on Chemical Physiology and Pathology Vol. 11; pp. 216 - 221
• Main Authors: YANO, Atsuo, TANAKA, Takehiko
• Format: Journal Article
• Language: Japanese
• Published: Japan Society of Clinical Chemistry 1972
• ISSN: 0386-3417; 2187-4085
• DOI: 10.14921/jscc1971a.11.0_216

Energy metabolism increases after protein food has been ingested. This phenomenon was called specific dynamic action (S. D. A.) by M. Rubner in 1902. The mechanism of S. D. A. is not yet clear, though different hypotheses have been proposed by various laboratories. We have devised a continuous recording analyzer for contents of oxygen and carbondioxide in respiratory gas. The following results were obtained by continuous measurement of energy metabolism and Respiratory Quotient (R. Q.) of albino rats. (1) Increase in O2 consumption and R. Q. began almost immediately after rats started to ingest protein diets. O2 consumption reached to its maximum within 10-15 min, then gradually decreased and reached its constant level at about 15-30% higher than the basal metabolism in about 30 min. Thereafter this high level was maintained at least for 60 min. (2) Passage of food ingested was inspected by X-ray in rat fed on a diet containing 25% of barium sulfate. Most of ingested food were still in stomach and only a little amount of food were in duodenum and upper jejunum over 45 min after food ingestion have been started. Accordingly changes in energy metabolism and R. Q. has occurred in rats perhaps before digestion and absorption of the nutrient. (3) Value of S. D. A. increased in pallarel with increasing contents of protein in diet, but the maximum value of R. Q. slightly decreased inversely. (4) Value of S. D. A. was higher in the rats which had ingested casein as a nitrogen source than in those which had ingested amino acid mixture simulated to casein composition. (5) No significant difference in value of S. D. A. were observed among the rats having ingested various kinds of proteins, the biological value of which ranged from 24 to 65. (6) Value of S. D. A. did not change in adrenalectomized rats. Value of S. D. A. markedly decreased in alloxan diabetic rats and, in addition, the maximum value of R. Q. also decreased in severe diabetic rats. (7) Intraperitoneal administration of insulin causes increases in O2 consumption and R. Q. similar to that upon food ingestion. Administration of insulin together with glucagon or pancreozymin causes a faster and greater increase in energy metabolism as well as R. Q. value. (8) S. D. A. was not observed in rats after they had undergone a ventromedial hypothalamic lesion.