Serum Citric Acid after Ingestion of Glucose in Normal and Starved Subjects.

During starvation or carbohydrate deprivation certain changes take place in the metabolic pattern of animals and human beings, leading to "abnormalities" in carbohydrate metabolism. These changes reveal themselves in manifold ways: the glucose tolerance curve after carbohydrate deprivation is high and prolonged (1-4), and after severe starvation the RQ response to administered glucose is low or absent (5). Glucose uptake by the isolated rat diaphragm has been shown to be reduced in animals maintained for some time on a carbohydrate-free diet (6). The rise in blood pyruvic acid after glucose is late and prolonged in fasted human subjects (7). In hepatectomized animals the amount of glucose necessary to prevent the blood sugar from falling is reduced, and the survival time without glucose is prolonged, if a carbohydrate-free diet has been given before the experiment (8, 9). The spontaneous carbohydrate intake is low in rats after a period on a carbohydratefree diet (10).. The insulin content of the pancreas (11) and the blood sugar lowering effect of injected insulin (12) is reduced by carbohydrate deprivation. Recently it has been found that changes can be demonstrated on the enzymatic level. Muscle phosphorylase activity is increased, and the percentage of phosphorylase a is higher than normal in rats having fasted for one to five days (13). All these findings demonstrate that during carbohydrate deprivation profound changes are taking place in the hormonal and enzymatic pattern of carbohydrate metabolism, leading to the characteristic picture of starvation diabetes (14). In a recent report Natelson, Pincus and Lugovoy showed that the level of serum citric acid decreases after ingestion of glucose by normal human subjects (15). It was therefore thought of interest to determine the variations in serum citric acid when glucose was given to subjects having been fasted for some time. PROCEDURE AND METHODS