Intracellular factors determining the deposition of glycogen. The role of gluconeogenesis.

Abstract

The interrelationship between glycogen biosynthesis and do novo glucose formation in rats was studied by determining the oxaloacetic acid, ATP, and glycogen levels in the tissues of healthy starved rats and during the growth of transplantable hepatomas with different rates of growth. From the results obtained it was proposed that glycogen biosynthesis and de novo glucose formation are mutually enhanced and coupled processes. The validity of this conclusion was confirmed by in vitro model experiments involving the use of isolated-liver perfusion. Results of a multiple regression analysis indicated that the efficiency of gluconeogenesis and glycogen deposition is determined by the supply of oxygen to the liver, by the oxaloacetic acid content of this organ, and also by the degree of reduction of the glucose precursor. It was also shown that the ability of glucocorticoids and glucagon to enhance gluconeogenesis is dependent on the supply of oxygen to the liver. From the results of this in vivo and in vitro comparative study it is concluded that deposition of glycogen in the liver and possibly also in the brain is determined by the efficiency of gluconeogenesis.