Abstract
In earlier studies it has been demonstrated that deuterium may be retained on the betahydroxybutyrate molecule excreted after feeding deuterobutyric acid to rats. 1 When the α,β-dideutero acid was fed, only 4.2 atoms% were retained, while after feeding the β,γ-dideuterobutyric acid, an average of 22.5% of the excreted betahydroxybutyrate contained deuterium.
In order to determine which part of the caproic acid molecule is convertible to acetone bodies, a study of the deuterium content of betahydroxybutyric acid excreted in the urine after the feeding of the α,β- and β,γ-dideuterocaproate has been made. The deutero acids were prepared by saturation of the corresponding unsaturated acids.
The α,β unsaturated acid was formed by condensation of butyr-aldehyde and malonic acid under the influence of pyridine as a base while the formation of the β,γ hexenoic acid was a condensation of the same substances with triethanolamine as a base. They were identified by saponification numbers, boiling points, indices of refraction, and the rate of iodine uptake of the acids and their corresponding ethyl esters.
The acids were fed by stomach tube in the form of their sodium salts to female rats previously fasted 72 hours. The amounts administered were equivalent to 150 mg per 100 sq cm (calculated as acetone) per day in 2 divided doses. The urines of 8 animals were pooled, the betahydroxybutyric acid separated by acidification, extraction in butyl alcohol, and the subsequent extraction from this material as the sodium salt by means of sodium carbonate. The silver salt was then prepared. This was analyzed for betahydroxybutyric acid and its deuterium content. The results are shown in Table I.
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