No abstract

Activities of enzymes involved in glucose phosphorylation, glucokinase (EC 2.7.1.2.), hexokinase (EC 2.7.1.1.), glucose 6-phosphatase (EC 3.1.3.9.), and in NADPH production, glucose-6-phosphate dehydrogenase (EC 1.1.1.49), 6-phospho-gluconate dehydrogenase (EC 1.1.1.44), NADP Malate-dehydrogenase (EC 1.1.1.40), were studied in rat liver and adipose tissue during fasting-refeeding and protein depletion-repletion. Fasting induced an increased activity of glucose-6-phosphatase and a sharp decrease in all other activities in both liver and adipose tissue hexokinase, dehydrogenases of the pentose shunt and NADP-Malate dehydrogenase. These activities have long been associated with adaptative hyperlipogenesis. In our experiments adaptation was more evident in liver than adipose tissue. On the other hand, protein-depletion alone did not change glucose availability or glucose 6-phosphatase activity. Protein repletion did not induce any hyperactivity of glucokinase, adipose tissue hexokinase, nor dehydrogenases, evidencing a lack of hyper-lipogenesis.