Metabolism of C¹⁴-labeled acetone, acetate and palmitate in fasted pregnant and nonpregnant guinea pigs

¹ Division of Veterinary Physiology and Pharmacology, University of Minnesota, St. Paul, Minnesota

Metabolism of acetone-2-C¹⁴, Na acetate-2-C¹⁴, and Na palmitate-1-C¹⁴ was compared in normal and pregnant ketotic guinea pigs. Expired CO₂, lipids, urine, liver tissue and acetone bodies were quantitated and assayed for radioactivity. After acetone-C¹⁴ injections, pregnant ketotic, as well as nonpregnant guinea pigs injected with carrier acetone, metabolized markedly less C¹⁴ as the blood concentration of acetone was progressively elevated. The data showed that the actual milligrams of free acetone utilized remained fairly constant regardless of the size of the body acetone pool. After acetate-C¹⁴ injections, pregnant fasted guinea pigs utilized less C¹⁴ for CO₂ excretion and more C¹⁴ for biosynthesis than the nonpregnant fasted group. The difference in CO₂ specific activity with regard to size of the body acetate pool is discussed. After palmitate-C¹⁴ injections, the mean specific activity of the CO₂ was greater in the pregnant fasted than in the nonpregnant fasted animals. Since the liver fat content of the former was lower, the data indicate a faster turnover rate of a smaller fatty acid pool.