Clinical Chemistry, Vol 17, 810-817, Copyright © 1971 by the American Association for Clinical Chemistry

Effects of Irradiation or Traumatic Injuries on Propionate Metabolism in Rats

¹ Department of Biochemistry, Lovelace Foundation for Medical Education and Research, Albuquerque, N. Mex. 87108.

The rate of ¹⁴CO₂ production in vivo by rats after injection with 10 µCi of 1-¹⁴C-propionate is useful in selecting uniform groups of animals for studies of experimental injuries and in investigating dose—response relationships in animals exposed to injury. The response appeared to be most sensitive to lung injury induced by air-blast, but was also sensitive to critical levels of irradiation or thermal exposure. Irradiation with ⁶⁰Co -irradiation significantly depressed ¹⁴CO₂ production, the degree and persistence being doserelated. Critical burn injuries resulted in decreased rates of ¹⁴CO₂ production, which decreased as the clinical condition of animals deteriorated. Because the most significant decrease occurred within the first 30 min, measurement of the initial rate of ¹⁴C-propionate utilization was sufficient to detect altered metabolic states. High-resolution radioanalyses of urinary organic acids show the major ones excreted to be propionate and its immediate catabolites, methylmalonate and succinate, in both control animals and animals exposed to experimental injuries. These results suggest that propionate metabolism may be one of the sites in intermediary metabolism that is sensitive to alteration by experimental injuries and thus may be one of the more sensitive metabolic indicators.