Control of gluconeogenesis and of enzymes of glycogen metabolism in isolated rat hepatocytes. A parallel study of the effect of phenylephrine and of glucagon.
Control of gluconeogenesis and of enzymes of glycogen metabolism in isolated rat hepatocytes. A parallel study of the effect of phenylephrine and of glucagon.
复制标题
离体大鼠肝细胞中糖异生和糖原代谢酶的控制。
DOI：
10.1042/bj1760791
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发表时间：
1978
期刊：
影响因子：
--
通讯作者：
H. Hers
中科院分区：
文献类型：
--
作者：
L. Hue;J. E. Felíu;H. Hers
采用饲养大鼠肝脏分离的肝细胞，比较研究了苯肾上腺素、加压素和胰高血糖素对糖异生和糖原代谢酶的影响。当肝细胞在Ca（2+）存在下孵育时，苯肾上腺素对丙酮酸糖异生的刺激程度低于胰高血糖素，但与该激素相比，它不影响蛋白激酶和丙酮酸激酶的活性，也不影响磷酸烯醇丙酮酸的浓度，也不减少[6-(3)H]葡萄糖中(3)H(2)O的释放。抗利尿激素的作用与苯肾上腺素相似。苯肾上腺素和胰高血糖素也刺激了果糖的糖异生，更明显的是，胰高血糖素以果糖转化为乳酸为代价。胰岛素能拮抗苯肾上腺素对丙酮酸糖异生的刺激作用。当从培养液中去除Ca（2+）时，苯肾上腺素仍然刺激丙酮酸糖异生，但它也引起蛋白激酶的激活和丙酮酸激酶的失活；因此，磷酸烯醇丙酮酸浓度增加，相反，加压素对所有这些参数都没有影响。葡萄糖或Ca（2+）的缺乏降低了苯肾上腺素引起糖原磷酸化酶的活性；当这两个条件结合在一起时，它就被废除了。糖原合成酶在Ca（2+）存在或不存在的情况下被苯肾上腺素灭活，尽管可能是通过不同的机制。
Hepatocytes isolated from the livers of fed rats were used for a comparative study of the effects of phenylephrine, vasopressin and glucagon on gluconeogenesis and on enzymes of glycogen metabolism. When hepatocytes were incubated in the presence of Ca(2+), phenylephrine stimulated gluconeogenesis from pyruvate less than did glucagon, but, in contrast with this hormone, it did not affect the activities of protein kinase and pyruvate kinase, nor the concentration of phosphoenolpyruvate, and it did not decrease the release of (3)H(2)O from [6-(3)H]glucose. The effects of vasopressin were similar to those of phenylephrine. Gluconeogenesis from fructose was also stimulated by phenylephrine and, more markedly, by glucagon at the expense of the conversion of fructose into lactate. Insulin was able to antagonize the stimulatory effect of phenylephrine on gluconeogenesis from pyruvate. When Ca(2+) was removed from the incubation medium, phenylephrine still stimulated gluconeogenesis from pyruvate, but it also caused an activation of protein kinase and an inactivation of pyruvate kinase; accordingly, the concentration of phosphoenolpyruvate was increased, and, in contrast, vasopressin had no effect on all these parameters. The property of phenylephrine to cause the activation of glycogen phosphorylase was decreased by glucose or by the absence of Ca(2+); it was abolished when these two conditions were combined. Glycogen synthase was inactivated by phenylephrine in the presence or the absence of Ca(2+), although presumably by different mechanisms.