Urinary Excretion of Pyruvic Acid, a-Ketoglutaric Acid, and Oxaloacetic Acid in Scurvy

Scurvy is associated with abnormal carbohydrate metabolism and diminished production of insulin (1). Banerjee et al. (2) observed increased accumulation of citrate, malate, and lactate in the tissues of scorbutic guinea pigs. This was possibly due to the insulin insufficiency associated with scurvy since prolonged injection of insulin to scorbutic guinea pigs diminished the tissue concentrations of these acids. Banerjee et al. (3) also observed decreased succinic acid dehydrogenase and malic acid dehydrogenase activity in tissues of scorbutic guinea pigs, which came to the normal level after the scorbutic animals received prolonged injection of insulin. Increased accumulation of citrate in tissues of scorbutic animals supposedly due to a decreased activity of the enzyme or enzymes intimately concerned with citrate oxidation through the tricarboxylic acid cycle. It was, therefore, of interest to study the metabolism of the members of the tricarboxylic acid cycle in scurvy. In the present investigation, the urinary excretions of the keto acids, pyruvic acid, cu-ketoglutaric acid, and oxaloacetic acid, were estimated in the urine of normal and scorbutic guinea pigs before and after they were fed citric, succinic, and malic acids. As insulin has marked effects on the enzyme systems of the Krebs cycle (4) the effects of prolonged injection of insulin in scorbutic guinea pigs on the excretion of keto acids were also studied.