DIFFERENTIAL METABOLIC REQUIREMENT FOR INITIATION AND AUGMENTATION OF INSULIN RELEASE BY GLUCOSE - A STUDY WITH RAT PANCREATIC-ISLETS
DIFFERENTIAL METABOLIC REQUIREMENT FOR INITIATION AND AUGMENTATION OF INSULIN RELEASE BY GLUCOSE - A STUDY WITH RAT PANCREATIC-ISLETS
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DOI：
10.1677/joe.0.1430497
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发表时间：
1994-12-01
影响因子：
4
通讯作者：
HASHIZUME, K
中科院分区：
文献类型：
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作者：
ISHIHARA, F;AIZAWA, T;HASHIZUME, K
胰岛素释放，葡萄糖利用（（H2O）-H-3从[5-H-3]葡萄糖形成），和葡萄糖氧化（（CO2）-C-14从[C-14（U）]葡萄糖形成），分别在37 ℃下禁食96小时大鼠的胰岛和22 ℃下进食大鼠的胰岛中测定，使用37 ℃下孵育的进食大鼠的胰岛作为对照。在禁食96小时的大鼠胰岛和在22 ℃孵育的进食大鼠胰岛中，我们不能证明对高达16.7 mmol/l的高葡萄糖浓度有显著的胰岛素释放反应。然而，16.7 mmol/l葡萄糖明显增加了这些胰岛中由去极化浓度（50 mmol/l）的K+引起的胰岛素释放：即16.7 mmol/l葡萄糖加50 mmol/l K+比单独50 mmol/l K+产生显著更大的胰岛素释放。葡萄糖的利用和氧化的胰岛细胞被抑制96小时禁食的大鼠或通过降低孵育温度至22摄氏度，和去极化与K+在50 mmol/l并没有在所有增加葡萄糖的利用和氧化的胰岛。因此，我们得出结论，减少葡萄糖代谢的胰岛从禁食大鼠和那些在低温下孵育消除启动，但不是增强，胰岛素释放的16.7 mmol/l葡萄糖。数据表明，胰岛素释放起始的代谢阈值显著高于葡萄糖增加释放的代谢阈值。
Insulin release, glucose utilization ((H2O)-H-3 formation from [5-H-3]glucose), and glucose oxidation ((CO2)-C-14 formation from [C-14(U)]glucose) were determined in pancreatic islets from 96-h fasted rats at 37 degrees C and those from fed rats at 22 degrees C, using the islets from fed rats incubated at 37 degrees C as controls. In the islets from 96-h fasted rats and those from fed rats incubated at 22 degrees C, we could not demonstrate significant insulin release in response to high glucose concentrations of up to 16.7 mmol/l. However, 16.7 mmol/l glucose clearly augmented insulin release caused by a depolarizing concentration (50 mmol/l) of K+ in these islets: i.e. 16.7 mmol/l glucose plus 50 mmol/l K+ produced significantly greater insulin release than 50 mmol/l K+ alone. Glucose utilization and oxidation by the islet cells were suppressed by 96-h fasting of the rats or by lowering the incubation temperature to 22 degrees C, and depolarization with K+ at 50 mmol/l did not at all augment glucose utilization and oxidation by the islets. Thus we conclude that reduction of glucose metabolism in islets from fasted rats and in those incubated at low temperature eliminated initiation, but not augmentation, of insulin release by 16.7 mmol/l glucose. The data indicate that the metabolic threshold for the initiation of insulin release is significantly higher than it is for the augmentation of release by glucose.