Control of Glycolysis and Gluconeogenesis in Liver and Kidney Cortex

Abstract

This chapter discusses the control of glycolysis and gluconeogenesis in liver and kidney cortex. Liver and kidney cortex tissues appear to be unique in higher animals—that is, they possess the enzymatic potential for both glucose synthesis from noncarbohydrate precursors (gluconeogenesis), and glucose degradation by the glycolytic pathway. The functioning of both these pathways is demonstrated unequivocally in the perfused kidney, kidney cortex slices, the perfused liver, and liver slices. Gluconeogenesis is important when the dietary supply of glucose does not satisfy the metabolic demands of the animal; under these conditions glucose is required by the central nervous system, the red blood cells, and other tissues which cannot obtain all their energy requirements from fatty acid or ketone body oxidation. The gluconeogenesis is also important in the removal of excessive quantities of glucose precursors from the blood. The experimental approach to the study of gluconeogenesis and the theories of metabolic control are based on the assumption that the rate of glycolysis in these tissues is low, so that there is little impedance to the synthesis of glucose. The chapter also discusses the regulatory factors that change enzyme activity rapidly.