Oviasu O A, Whitton P D
Biochem J. 1984 Nov 15;224(1):181-6. doi: 10.1042/bj2240181.
A detailed study of the control of liver pyruvate dehydrogenase activity by various hormones was carried out with perfused liver and isolated hepatocytes. Vasopressin produced a significant increase in the enzyme activity in fed rats, and the time course and sensitivity of the response was similar to that of glycogen phosphorylase a. The enzyme from starved animals was resistant to hormonal activation. The possible factors involved in the above effects are discussed. Angiotensin and phenylephrine also increased pyruvate dehydrogenase activity, and the magnitude of the response was of the same order as that to vasopressin by the liver enzyme. The effects of these hormones on pyruvate dehydrogenase activity were critically dependent on extracellular Ca2+, thus suggesting a role for this ion in the mechanism of action of the hormones. Insulin did not appear to have a role in the control of the enzyme activity, as shown by its lack of effect on the enzyme. Glucagon, in contrast with previous reports, produced a rapid, transient and significant increase in pyruvate dehydrogenase activity. The physiological importance of the above effects is discussed.
利用灌注肝脏和分离的肝细胞,对各种激素对肝脏丙酮酸脱氢酶活性的控制进行了详细研究。在喂食的大鼠中,血管加压素使该酶活性显著增加,反应的时间进程和敏感性与糖原磷酸化酶a相似。饥饿动物的酶对激素激活具有抗性。讨论了上述效应中可能涉及的因素。血管紧张素和去氧肾上腺素也增加了丙酮酸脱氢酶活性,反应幅度与肝脏酶对血管加压素的反应幅度相同。这些激素对丙酮酸脱氢酶活性的影响严重依赖细胞外Ca2+,因此表明该离子在激素作用机制中起作用。胰岛素似乎在酶活性的控制中不起作用,这表现为它对该酶没有影响。与先前的报道相反,胰高血糖素使丙酮酸脱氢酶活性迅速、短暂且显著增加。讨论了上述效应的生理重要性。