Staddon J M, McGivan J D
Biochem J. 1984 Jan 15;217(2):477-83. doi: 10.1042/bj2170477.
The hormonal regulation of gluconeogenesis and ureogenesis in isolated rat hepatocytes with 5 mM-proline as precursor was studied, with the following results. (1) The formation of glucose and urea in a 30 min interval were stimulated more by vasopressin than by glucagon, and the effects of the two hormones in combination were additive. (2) The rates of gluconeogenesis during the 30 min were constant under control, glucagon-stimulated and glucagon-plus-vasopressin-stimulated conditions. The stimulated rate in the presence of vasopressin diminished with time; glucagon in combination with vasopressin prevented this diminution, resulting in an additive effect. (3) Coincident with these changes in gluconeogenesis, vasopressin caused a decrease in cell oxoglutarate concentration, which, in contrast with the decrease caused by glucagon, was greater, but not sustained unless glucagon was also present. Changes in cell glutamate concentration similar to those observed for oxoglutarate occurred. (4) The data suggest that activation of oxoglutarate dehydrogenase (EC 1.2.4.2) by glucagon and vasopressin by different mechanisms may explain the relative effects of the hormones alone and in combination on gluconeogenesis from proline.
以5 mM脯氨酸作为前体，对分离的大鼠肝细胞中糖异生和尿素生成的激素调节进行了研究，结果如下。(1) 在30分钟的时间间隔内，血管加压素比胰高血糖素更能刺激葡萄糖和尿素的生成，两种激素联合使用的效果是相加的。(2) 在对照、胰高血糖素刺激和胰高血糖素加血管加压素刺激的条件下，30分钟内糖异生的速率是恒定的。血管加压素存在时的刺激速率随时间降低；胰高血糖素与血管加压素联合使用可防止这种降低，从而产生相加效应。(3) 与糖异生的这些变化同时发生的是，血管加压素导致细胞中草酰戊二酸浓度降低，与胰高血糖素引起的降低相比，这种降低更大，但除非同时存在胰高血糖素，否则不会持续。细胞谷氨酸浓度发生了与草酰戊二酸类似的变化。(4) 数据表明，胰高血糖素和血管加压素通过不同机制激活草酰戊二酸脱氢酶（EC 1.2.4.2），这可能解释了激素单独及联合作用对脯氨酸糖异生的相对影响。
