Serum factor in fasted rats inhibiting carbohydrate metabolism in the isolated diaphragm

Abstract
A factor has been found in the serum of fasted rats which inhibits glucose uptake and glycogen synthesis in the isolated rat diaphragm. It does not affect CO2 production or O2 uptake. It is nondialyzable, stable in the cold and also stable when heated to 58°C for 1 hour. It was found in Cohn fraction IV-V. Its action did not resemble any of the known hormones, nor could it be identified as one of the inhibitory factors found in diabetic serum.