Abstract
Von Euler and Högberg 1 reported that the administration of citric acid produces a delayed decrease in the concentration of pyruvic acid in the blood. The principal evidence was from a small series of experiments with rats receiving oral or subcutaneous dosages of sodium citrate. Emphasis, however, was placed on a single experiment with a normal man whose blood pyruvate was lowered to 22% of the original level 12 to 15 hours after the oral ingestion of 2 g of citric acid as the sodium salt. The blood pyruvate change in this man was stated to be accompanied by indications of a profound general disturbance including sweating, shivering, and fever.
Apart from the suggestion of important theoretical relations this report is of interest because of the growing use of blood pyruvate measurements in the study of thiamine deficiency and the fact that the citric acid dosage employed is scarcely heroic. Two grams of citric acid would be supplied by one large lemon or by 200 cc of orange juice. 2
In this Laboratory this question was studied in 5 experiments on 3 normal young men who had been maintained on a carefully standardized dietary for several months. In each experiment a blood sample was drawn before breakfast at 8:00 a.m. and 3 g of citric acid as Na citrate were administered orally in 200 cc of orange juice on the same day at 6.00 p.m. The final blood sample was taken before breakfast on the following morning at 8:00 a.m., that is, 14 hours after the citric acid administration. The blood samples were drawn from veins in the antecubital fossa, Pyruvate was estimated in duplicate by the method of Friedemann and Haugen. 3
The results are summarized in Table I.
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