Berts A, Ball A, Gylfe E, Hellman B
Department of Medical Cell Biology, Uppsala University, Sweden.
Biochim Biophys Acta. 1996 Feb 2;1310(2):212-6. doi: 10.1016/0167-4889(95)00173-5.
The cytoplasmic Ca2+ concentration ([Ca2+]i) was continuously monitored in single glucagon-producing alpha 2-cells isolated from the mouse pancreas and later identified by immunostaining. Up to 60% of the alpha 2-cells exhibited spontaneous [Ca2+]i oscillations (frequency 0.1-0.3/min) in a medium containing 3 mM glucose. In originating from a basal level of 60-100 nM, reaching peak values of 300-400 nM and promptly disappearing after blocking voltage-dependent Ca2+ channels with methoxyverapamil, the oscillations resembled those in insulin-releasing beta-cells stimulated by glucose. The oscillatory activity was suppressed when combining elevation of glucose to 20 mM with the addition of 2-2000 ng/ml insulin. Whereas 10 mM of L-arginine or l-glycine transformed the oscillations into sustained elevation of [Ca2+]i, there was no response to 1 mM tolbutamide or 0.1-1 mM gamma-aminobutyric acid. The observations that alpha 2-cells differ from islet cells secreting insulin and somatostatin in responding to adrenaline with mobilisation of intracellular calcium can be used for their rapid identification. It is suggested that the oscillations reflect periodic entry of Ca2+ due to variations of the membrane potential.
对从小鼠胰腺分离出的单个产胰高血糖素的α2细胞的细胞质钙离子浓度（[Ca2+]i）进行连续监测，随后通过免疫染色进行鉴定。在含有3 mM葡萄糖的培养基中，高达60%的α2细胞表现出自发性[Ca2+]i振荡（频率0.1 - 0.3次/分钟）。这些振荡起始于60 - 100 nM的基础水平，峰值达到300 - 400 nM，在用甲氧维拉帕米阻断电压依赖性Ca2+通道后迅速消失，类似于葡萄糖刺激的胰岛素释放β细胞中的振荡。当将葡萄糖浓度提高到20 mM并添加2 - 2000 ng/ml胰岛素时，振荡活性受到抑制。而10 mM的L - 精氨酸或L - 甘氨酸将振荡转变为[Ca2+]i的持续升高，对1 mM甲苯磺丁脲或0.1 - 1 mMγ-氨基丁酸无反应。α2细胞在对肾上腺素反应时通过动员细胞内钙与分泌胰岛素和生长抑素的胰岛细胞不同，这一观察结果可用于它们的快速鉴定。有人提出，这些振荡反映了由于膜电位变化导致的Ca2+周期性内流。
