Studies on carbohydrate metabolism in scorbutic guinea pigs.

Scurvy is associated with disturbed carbohydrate metabolism. A diminished glucose tolerance has been observed by several workers in scorbutic guinea pigs (l-4), in scorbutic monkeys (5), and in human subjects with low blood ascorbic acid level (6, 7). Several workers (2,4, 8) have reported a decrease in the liver and muscle glycogen content of scorbutic guinea pigs. Banerjee and Ghosh (9) have observed a decreased liver and muscle hexokinase activity in scurvy. Lahiri and Banejee (10) have further shown a decreased turnover rate of the phosphorylated intermediates of the carbohydrate metabolism in scurvy. Banerjee and his coworkers have also observed degenerative changes in the islets of Langerhans (II), and diminished insulin content of the pancreas in scurvy (4). According to them, the disturbance in carbohydrate metabolism in scurvy may be mainly due to diminished insulin production by the pancreas, a view not subscribed to by other workers (12, 13). At present, there are increasing evidences that insulin is involved in the intermediate metabolism of carbohydrates at the level of the Krebs cycle (14-19). It is possible that in scurvy there may be a disturbance in carbohydrate metabolism at the level of the Krebs cycle, due either to diminished insulin production or to the direct effect of the lack of vitamin C on the enzyme systems concerned with the oxidation of intermediates through the Krebs cycle. In the present paper, the effect of injections of insulin on glucose tolerance and on liver and muscle glycogen contents in scorbutic guinea pigs is reported. As a preliminary study of the metabolism of intermediates through the Krebs cycle, the tissue content of ol-keto acids and of citric, malic, and lactic acids of normal, scorbutic, and insulin-treated scorbutic guinea pigs has also been presented.