Tjioe T O, Bouman P R
Horm Metab Res. 1976 Jul;8(4):261-6. doi: 10.1055/s-0028-1093651.
Pancreatic islets of fed, 24 hr and 72 hr fasted rats were incubated with [3H]-L-phenylalanine at verious concentrations of glucose. Total islet protein was isolated by TCA-precipitation, proinsulin-insulin by polyacrylamide gel electrophoresis. The incorporation of label was expressed per mug dry islet weight. Fasting for 24 hr reduced the incorporation of label into (pro)insulin at glucose 3 mg/ml, but not at glucose 1 mg/ml. After 72 hr of fasting the incorporation into (pro)insulin was decreased both at glucose 1 and 3 mg/ml and the slope of the dose-response curve for glucose stimulation was reduced by 31%. In contrast, fasting caused the incorporation into total islet protein to increase. A similar tendency was observed in an unidentified protein fraction, which failed to migrate from the spacer gel on disc electrophoresis. Fasting did not affect the islet DNA content per mug dry weight. These results suggest that fasting reduces the rate of insulin biosynthesis by decreasing the glucose sensitivity of this process. Fasting may stimulate, however, the biosynthesis of an unidentified islet protein component.
将喂食的、禁食24小时和72小时的大鼠的胰岛在不同葡萄糖浓度下与[3H]-L-苯丙氨酸一起孵育。通过三氯乙酸沉淀分离总胰岛蛋白，通过聚丙烯酰胺凝胶电泳分离胰岛素原-胰岛素。标记掺入量以每微克干胰岛重量表示。禁食24小时会降低葡萄糖浓度为3毫克/毫升时标记掺入（胰岛素原）胰岛素的量，但在葡萄糖浓度为1毫克/毫升时不会。禁食72小时后，葡萄糖浓度为1和3毫克/毫升时，（胰岛素原）胰岛素的掺入量均降低，并且葡萄糖刺激的剂量反应曲线斜率降低了31%。相反，禁食导致总胰岛蛋白的掺入量增加。在圆盘电泳中未能从间隔凝胶迁移的一种未鉴定的蛋白组分中也观察到了类似趋势。禁食不影响每微克干重的胰岛DNA含量。这些结果表明，禁食通过降低该过程的葡萄糖敏感性来降低胰岛素生物合成速率。然而，禁食可能会刺激一种未鉴定的胰岛蛋白组分的生物合成。
