Watford M
Division of Nutritional Sciences, Cornell University, Ithaca, NY 14853.
J Nutr. 1989 Feb;119(2):319-22. doi: 10.1093/jn/119.2.319.
In chickens, the kidney possesses a distinct cytosolic phosphoenolpyruvate carboxykinase activity which is not found in the liver. This activity is subject to long-term regulation by diet and changes in acid-base status. The activity is increased during starvation or metabolic acidosis. In addition, an unidentified component of some standard chicken diets results in altered activity. Using a specific cDNA probe the abundance of PEPCK mRNA has been determined in chicken kidney in vivo and in vitro. The abundance of PEPCK mRNA in chicken kidney increases during starvation and is rapidly decreased after refeeding carbohydrate. In isolated kidney tubules the abundance of the mRNA is increased after incubation with glucocorticoids, dibutyryl cAMP or hormones acting via changes in the concentration of cAMP (parathyroid hormone, epinephrine). Phorbol esters or hormones acting via calcium-dependent mechanisms were without effect. The results support the hypothesis that in the chicken the kidney is the major site of gluconeogenesis from substrates other than lactate and thus plays an important role in the maintenance of glucose homeostasis.
在鸡体内，肾脏具有一种独特的胞质磷酸烯醇式丙酮酸羧激酶活性，而肝脏中不存在这种活性。该活性受饮食和酸碱状态变化的长期调节。在饥饿或代谢性酸中毒期间，该活性会增加。此外，某些标准鸡饲料中一种不明成分会导致活性改变。使用特异性cDNA探针，已在体内和体外测定了鸡肾脏中磷酸烯醇式丙酮酸羧激酶（PEPCK）mRNA的丰度。鸡肾脏中PEPCK mRNA的丰度在饥饿期间增加，重新投喂碳水化合物后迅速降低。在分离的肾小管中，与糖皮质激素、二丁酰环磷腺苷（dibutyryl cAMP）或通过环磷腺苷浓度变化起作用的激素（甲状旁腺激素、肾上腺素）孵育后，mRNA的丰度增加。佛波酯或通过钙依赖机制起作用的激素则没有影响。这些结果支持了这样一种假说，即在鸡体内，肾脏是除乳酸以外底物进行糖异生的主要部位，因此在维持葡萄糖稳态中起重要作用。
