灌注大鼠肝脏中低浓度循环葡萄糖对磷酸烯醇丙酮酸羧激酶（鸟苷三磷酸）活性的刺激作用。

Stimulation of phosphoenolpyruvate carboxykinase (guanosine triphosphate) activity by low concentrations of circulating glucose in perfused rat liver.

作者信息

Moreno F J, Sánchez-Urrutia L, Medina J M, Sánchez-Medina F, Mayor F

出版信息

Biochem J. 1975 Jul;150(1):51-8. doi: 10.1042/bj1500051.

DOI:10.1042/bj1500051

PMID:173301

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC1165703/

Abstract

After nicotinic acid treatment, rat liver glycogen is depleted and phosphoenolpyruvate carboxykinase activity increased, to about twice the initial value. 2. The increase in phosphoenolpyruvate carboxykinase activity promoted by nicotinic acid is prevented by cycloheximide or actinomycin D, suggesting that this effect is produced by synthesis of the enzyme de novo. 3. Despite the enhancement of phosphoenolpyruvate carboxykinase activity and glycogen depletion, which occurs 5h after the injection of nicotinic acid, the gluconeogenic capacity of liver is low and considerably less than the values found in rats starved for 48h. 4. When the livers of well-fed rats are perfused in the presence of low concentrations of glucose, the activity of phosphoenolpyruvate carboxykinase significantly increases compared with the control. 5. This increase is not related to the glycogen content, but seems to be also the result of synthesis of the enzyme de novo, since this effect is counteracted by previous treatment with cycloheximide or actinomycin D. 6. Phosphoenolpyruvate carboxykinase activity is not increased in the presence of low concentrations of circulating glucose when 40 mM-imidazole (an activator of phosphodiesterase) is added to the perfusion medium. 7. Addition of dibutyryl cyclic AMP to the perfusion medium results in an increase in phosphoenolpyruvate carboxykinase activity, in spite of the presence of normal concentrations of circulating glucose. On the other hand, the concentration of cyclic AMP in the liver increases when that of glucose in the medium is low. 8. These results suggest that, in the absence of hormonal factors, the regulation of phosphoenolpyruvate carboxykinase can be accomplished by glucose itself, inadequate concentrations of it resulting in the induction of the enzyme. The mediator in this regulation, as in hormonal regulation, seems to be cyclic AMP.

摘要

用烟酸处理后，大鼠肝脏糖原耗竭，磷酸烯醇式丙酮酸羧激酶活性增加，约为初始值的两倍。2. 环己酰亚胺或放线菌素D可阻止烟酸促进的磷酸烯醇式丙酮酸羧激酶活性增加，这表明此效应是由该酶的从头合成产生的。3. 尽管在注射烟酸5小时后出现了磷酸烯醇式丙酮酸羧激酶活性增强和糖原耗竭的情况，但肝脏的糖异生能力较低，且远低于饥饿48小时的大鼠的数值。4. 当在低浓度葡萄糖存在的情况下灌注喂食良好的大鼠的肝脏时，磷酸烯醇式丙酮酸羧激酶的活性与对照组相比显著增加。5. 这种增加与糖原含量无关，但似乎也是该酶从头合成的结果，因为先前用环己酰亚胺或放线菌素D处理可抵消这种效应。6. 当向灌注培养基中添加40 mM咪唑（一种磷酸二酯酶激活剂）时，在低浓度循环葡萄糖存在的情况下，磷酸烯醇式丙酮酸羧激酶活性不会增加。7. 向灌注培养基中添加二丁酰环磷腺苷会导致磷酸烯醇式丙酮酸羧激酶活性增加，尽管存在正常浓度的循环葡萄糖。另一方面，当培养基中的葡萄糖浓度较低时，肝脏中环磷腺苷的浓度会增加。8. 这些结果表明，在没有激素因子的情况下，磷酸烯醇式丙酮酸羧激酶的调节可由葡萄糖自身完成，葡萄糖浓度不足会导致该酶的诱导。与激素调节一样，这种调节中的介质似乎是环磷腺苷。