Effects of Diphenylhydantoin upon the Plasma Free Fatty Acid Response Induced by Hormones.

Abstract

partially account for the observed difference between infused and expired carbon-14.About 33% of the radioactivity found in the urine was in the form of C02. However, identification of compounds containing the remaining radioactivity was not made. Rust et aZ (13) found radioactivity in urea of the urine of rats following injections of sodium bicarbonate-14.The close agreement between the half-life of blood CO:! and respiratory CO:! calculated from the exponential part of the curve ( Fig. 1 and 2 ) suggest that blood CO2 data may be used in studying oxidative rates of substrates. This would eliminate the respiratory stress of the animal due to the apparatus needed to collect expired air.The turnover rate was constant for the 3 experiments with a mean of 9.58 mecl/hr/kg of body weight. The mean CO2 space was 0.414 liter/kg body weight, which is about twice the extracellular volume. The amount of radioactivity found in the rumen would indicate that the rumen must be considered part of the C 0 2 space.Summary. The carbon dioxide pool system of sheep was evaluated by the constant infusion of sodium bicarbonate-C14 for a period of 4 hours. The specific activity of blood CO, plateaued during the final hour of infusion. Following infusion, the half-lives of blood and expired COs were 32.6 and 31 minutes, respectively. Mean turnover rate, turnover time and C 0 2 space were 9.58 meq/hr/ kg body weight, 46.8 minutes and 41.4% of body weight, respectively. Considerable radioactivity wits found in the rumen a t the end of the infusion period. These observations suggest a time of a t least 3 hours for complete labeling of the C 0 2 pool, of which the rumen is a part, and that blood C 0 2 data may be used as well as expired C02 data for substrate oxidation studies.