Dohm G L, Newsholme E A
Biochem J. 1983 Jun 15;212(3):633-9. doi: 10.1042/bj2120633.
Prolonged exercise increased the concentrations of the hexose phosphates and phosphoenolpyruvate and depressed those of fructose 1,6-bisphosphate, triose phosphates and pyruvate in the liver of the rat. Since exercise increases gluconeogenic flux, these changes in metabolite concentrations suggest that metabolic control is exerted, at least, at the fructose 6-phosphate/fructose 1,6-bisphosphate and phosphoenolpyruvate/pyruvate substrate cycles. Exercise increased the maximal activities of glucose 6-phosphatase, fructose 1,6-bisphosphatase, pyruvate kinase and pyruvate carboxylase in the liver, but there were no changes in those of glucokinase, 6-phosphofructokinase and phosphoenolpyruvate carboxykinase. Exercise changed the concentrations of several allosteric effectors of the glycolytic or gluconeogenic enzymes in liver; the concentrations of acetyl-CoA, ADP and AMP were increased, whereas those of ATP, fructose 1,6-bisphosphate and fructose 2,6-bisphosphate were decreased. The effect of exercise on the phosphorylation-dephosphorylation state of pyruvate kinase was investigated by measuring the activities under conditions of saturating and subsaturating concentrations of substrate. The submaximal activity of pyruvate kinase (0.5 mM-phosphoenolpyruvate), expressed as percentage of Vmax., decreased in the exercised animals to less than half that found in the controls. These changes suggest that hepatic pyruvate kinase is less active during exercise, possibly owing to phosphorylation of the enzyme, and this may play a role in increasing the rate of gluconeogenesis.
长时间运动增加了大鼠肝脏中己糖磷酸和磷酸烯醇丙酮酸的浓度，同时降低了1,6-二磷酸果糖、磷酸丙糖和丙酮酸的浓度。由于运动增加了糖异生通量，代谢物浓度的这些变化表明，至少在6-磷酸果糖/1,6-二磷酸果糖和磷酸烯醇丙酮酸/丙酮酸底物循环处施加了代谢控制。运动增加了肝脏中葡萄糖6-磷酸酶、1,6-二磷酸果糖酶、丙酮酸激酶和丙酮酸羧化酶的最大活性，但葡萄糖激酶、6-磷酸果糖激酶和磷酸烯醇丙酮酸羧激酶的活性没有变化。运动改变了肝脏中糖酵解或糖异生酶的几种变构效应物的浓度；乙酰辅酶A、ADP和AMP的浓度增加，而ATP、1,6-二磷酸果糖和2,6-二磷酸果糖的浓度降低。通过测量底物饱和和次饱和浓度条件下的活性，研究了运动对丙酮酸激酶磷酸化-去磷酸化状态的影响。以Vmax的百分比表示，运动动物中丙酮酸激酶的次最大活性（0.5 mM-磷酸烯醇丙酮酸）降至对照组的一半以下。这些变化表明，运动期间肝脏丙酮酸激酶活性较低，可能是由于该酶的磷酸化，这可能在增加糖异生速率中起作用。
