Plasma glucagon and insulin concentrations and hepatic phosphoenolpyruvate carboxykinase and pyruvate kinase activities during and upon adaptation of rats to a high protein diet.
Plasma glucagon and insulin concentrations and hepatic phosphoenolpyruvate carboxykinase and pyruvate kinase activities during and upon adaptation of rats to a high protein diet.
复制标题
大鼠适应高蛋白饮食期间和之后的血浆胰高血糖素和胰岛素浓度以及肝磷酸烯醇丙酮酸羧激酶和丙酮酸激酶活性。
DOI：
10.1093/jn/111.7.1173
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发表时间：
1981
期刊：
影响因子：
--
通讯作者：
R. Assan
中科院分区：
文献类型：
--
作者：
J. Peret;S. Foustock;M. Chanez;B. Bois;R. Assan
在40 d的高蛋白喂养期间，测定了成年大鼠血浆激素、葡萄糖和游离脂肪酸、肝糖原以及糖酵解和糖异生的两种关键酶。血浆胰岛素1天内下降，4天后恢复正常。胰高血糖素变化较慢，在第4天达到最大值，在24天内下降到接近对照组的水平。因此，胰岛素与胰高血糖素比值在第1、4和8天较低，在第24天接近正常。肝酶方面，磷酸烯醇丙酮酸羧激酶活性在第1天急剧升高，并持续升高40 d；丙酮酸激酶的l -同工酶虽然在第1天没有变化，但从第8天开始下降，占对照的15- 20%。在适应高蛋白饮食的大鼠中也测量了这些参数的昼夜变化。在这些动物中，血浆激素的日变化不太明显，但与对照组相比往往是相反的；白天高蛋白饮食组的胰岛素/胰高血糖素比值最高，而夜间对照组的胰岛素/胰高血糖素比值最高。24小时后，丙酮酸激酶活性与激素比值成正相关，磷酸烯醇丙酮酸羧激酶活性与激素比值成反比。我们得出结论，在适应高蛋白的大鼠中，与对照组一样，糖酵解和糖异生之间的昼夜平衡可能受到相同因素的调节，即胰岛素/胰高血糖素比率。
Plasma hormones, glucose and free fatty acids, liver glycogen and two key enzymes of glycolysis and gluconeogenesis were examined in adult rats during a 40-day period of high protein feeding. Plasma insulin fell within 1 day but returned to normal after 4 days. Glucagon changed more slowly, reaching a maximum on day 4 and declined to near the control value within 24 days. Consequently, the insulin to glucagon ratio was lower on days 1, 4 and 8 and was nearly normal on day 24. With respect to hepatic enzymes, phosphoenolpyruvate carboxykinase activity rose sharply on the 1st day and remained elevated for 40-day period; the L-isozyme of pyruvate kinase, although unchanged on the 1st day, decreased thereafter and from day 8 on represented 15--20% of control. Circadian variations in these parameters were also measured in rats adapted to the high protein diet. In such animals, the diurnal change in plasma hormones was less marked but tended to be inverted with respect to controls; the insulin/glucagon ratio was highest during daylight on high protein and in late night on the control diet. Over 24 hours, pyruvate kinase activity was related directly and phosphoenolpyruvate carboxykinase inversely to the hormone ratio. We concluded that in rats adapted to high protein, as in controls, the diurnal balance between glycolysis and gluconeogenesis is probably regulated by the same factor, namely the insulin/glucagon ratio.