Is there a role for osmotic events in the exocytotic release of insulin?
Is there a role for osmotic events in the exocytotic release of insulin?
复制标题
渗透事件在胰岛素胞吐释放中是否起作用？
作者：
M. Hermans;J. Henquin
在灌流的小鼠胰岛中，已经研究了胰岛素颗粒在胞吐过程中的渗透溶解的可能作用。通过加入400 mM蔗糖提高细胞外培养液的渗透压，可逆地抑制葡萄糖刺激的胰岛素释放。这种抑制伴随着从胰岛流出86Rb+或45Ca+的速率的降低。在无刺激性浓度葡萄糖存在的情况下，增加渗透压并恢复正常浓度可加速86Rb+和45Ca2+的外流，并增加基础胰岛素的释放。高渗并不能阻止葡萄糖浓度的升高而减少胰岛细胞的86Rb+外流，也不能阻止无钙培养液中45Ca2+的外流。但在有钙离子存在的情况下，葡萄糖对45Ca~(2+)外流的刺激作用被取消，对胰岛素释放的刺激几乎被抑制。高渗透压还通过至少部分不同的机制通过八种已知的实验条件强烈地削弱了刺激过程中胰岛素的释放。这些不同药物引起的45Ca~(2+)外流的变化也被高渗改变，无论是由于细胞内钙的直接动员还是继发于Ca~(2+)内流的增加。无论刺激的作用方式是什么，高渗透压对胰岛素释放的阻断与渗透事件参与胞吐作用是相容的。然而，伴随出现的钙离子处理的显著变化可能解释了释放的抑制，使得不可能证明它们在完整的胰岛细胞中的确切作用。
The possible role of an osmotic lysis of insulin granules during exocytosis has been studied in perifused mouse pancreatic islets. Raising the osmolarity of the extracellular medium by addition of 400 mM sucrose reversibly inhibited glucose-stimulated insulin release. This inhibition was accompanied by a decrease in the rates of 86Rb+ or 45Ca2+ efflux from the islets. Increasing the osmolarity and restoring a normotonic medium in the presence of a nonstimulatory concentration of glucose accelerated 86Rb+ and 45Ca2+ efflux and augmented basal insulin release in both the presence and absence of Ca2+. Hyperosmolarity did not prevent a rise in glucose concentration from decreasing 86Rb+ efflux from islet cells or from inhibiting 45Ca2+ efflux in Ca2+-free medium. However, the stimulation of 45Ca2+ efflux otherwise produced by glucose in the presence of Ca2+ was abolished, and the stimulation of insulin release was almost suppressed. Hyperosmolarity also strongly impaired the release of insulin during stimulation by eight experimental conditions known to act through at least partially different mechanisms. The changes in 45Ca2+ efflux brought about by these different agents were also altered by hyperosmolarity, whether they resulted from direct mobilization of intracellular Ca2+ or were secondary to increased Ca2+ influx. The blockade of insulin release by hyperosmolarity, whatever the mode of action of the stimulus, is compatible with the participation of osmotic events in exocytosis. However, the marked alterations in Ca2+ handling that occur concomitantly and might account for the inhibition of release make it impossible to demonstrate their exact role in intact islet cells.
化学渗透裂解在胰岛素胞吐释放中的作用。
影响因子：
4.8
作者：
Pace,CS;Smith,JS
通讯作者：
Smith,JS