Ribes G, Siegel E G, Wollheim C B, Renold A E, Sharp G W
Diabetes. 1981 Jan;30(1):52-5. doi: 10.2337/diab.30.1.52.
To study whether glucose affects total islet Ca content, 45Ca content was measured in isolated pancreatic islets, loaded with 45Ca++, during up to 48 h in tissue culture conditions. In islets maintained in 2.8 mM or 8.3 mM glucose the 45Ca content did not increase further after the 24 h, indicating that, at this time point, islets are in isotopic equilibrium. Islets maintained in 8.3 mM glucose had a significantly higher Ca content of 9 pmol/islet than the 5 pmol of islets maintained in 2.8 mM glucose. An increase in the glucose concentration from 2.8 mM to 8.3 mM after 24 h, in the continued presence of 45Ca++, caused a significant and rapid augmentation of the Ca content (+2.5 pmol/islet/5 min). Conversely, a decrease of the glucose concentration from 8.3 mM to 2.8 mM resulted in a rapid loss of cellular Ca. Thus, glucose rapidly affects the total Ca content of islets, the turnover of Ca amounting to approximately 10% of the total content per minute. Islets maintained in 8.3 mM glucose for 24 h exhibited a greater insulin release in response to 16.7 mM glucose than islets maintained for 24 h in 2.8 mM glucose. The increased response, however, was not correlative with the difference in Ca content.
为研究葡萄糖是否影响胰岛总钙含量，在组织培养条件下，对加载了45Ca++的分离胰岛进行长达48小时的培养，并测定其45Ca含量。在2.8 mM或8.3 mM葡萄糖中培养的胰岛，24小时后45Ca含量不再进一步增加，表明此时胰岛处于同位素平衡状态。在8.3 mM葡萄糖中培养的胰岛，其钙含量为9 pmol/胰岛，显著高于在2.8 mM葡萄糖中培养的胰岛的5 pmol。在持续存在45Ca++的情况下，24小时后将葡萄糖浓度从2.8 mM提高到8.3 mM，导致钙含量显著快速增加（+2.5 pmol/胰岛/5分钟）。相反，将葡萄糖浓度从8.3 mM降低到2.8 mM会导致细胞钙迅速流失。因此，葡萄糖能快速影响胰岛的总钙含量，钙的周转率约为每分钟总含量的10%。在8.3 mM葡萄糖中培养24小时的胰岛，对16.7 mM葡萄糖的胰岛素释放量比在2.8 mM葡萄糖中培养24小时的胰岛更大。然而，这种增加的反应与钙含量的差异无关。
