Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Oxford OX37LJ, UK.
Prog Biophys Mol Biol. 2011 Nov;107(2):224-35. doi: 10.1016/j.pbiomolbio.2011.06.009. Epub 2011 Jul 6.
When exposed to intermediate glucose concentrations (6-16 mol/l), pancreatic β-cells in intact islets generate bursts of action potentials (superimposed on depolarised plateaux) separated by repolarised electrically silent intervals. First described more than 40 years ago, these oscillations have continued to intrigue β-cell electrophysiologists. To date, most studies of β-cell ion channels have been performed on isolated cells maintained in tissue culture (that do not burst). Here we will review the electrophysiological properties of β-cells in intact, freshly isolated, mouse pancreatic islets. We will consider the role of ATP-regulated K⁺-channels (K(ATP)-channels), small-conductance Ca²⁺-activated K⁺-channels and voltage-gated Ca²⁺-channels in the generation of the bursts. Our data indicate that K(ATP)-channels not only constitute the glucose-regulated resting conductance in the β-cell but also provide a variable K⁺-conductance that influence the duration of the bursts of action potentials and the silent intervals. We show that inactivation of the voltage-gated Ca²⁺-current is negligible at voltages corresponding to the plateau potential and consequently unlikely to play a major role in the termination of the burst. Finally, we propose a model for glucose-induced β-cell electrical activity based on observations made in intact pancreatic islets.
当暴露于中等葡萄糖浓度（6-16mol/l）时，完整胰岛中的胰腺β细胞会产生动作电位爆发（叠加在去极化平台上），其间被去极化的电沉默间隔分开。这些振荡早在 40 多年前就首次被描述，一直令 β 细胞电生理学家感到好奇。迄今为止，大多数关于β细胞离子通道的研究都是在组织培养中进行的（不会爆发）的分离细胞上进行的。在这里，我们将回顾完整的、新分离的、小鼠胰腺胰岛中β细胞的电生理特性。我们将考虑 ATP 调节的 K ⁺ -通道（KATP-通道）、小电导 Ca²⁺ -激活的 K ⁺ -通道和电压门控 Ca²⁺ -通道在爆发中的作用。我们的数据表明，KATP-通道不仅构成了β细胞中葡萄糖调节的静息电导，还提供了可变的 K ⁺ 电导，影响动作电位爆发的持续时间和沉默间隔。我们表明，在与平台电位对应的电压下，电压门控 Ca²⁺ -电流的失活可以忽略不计，因此不太可能在爆发的终止中起主要作用。最后，我们根据在完整的胰腺胰岛中观察到的结果，提出了一个葡萄糖诱导的β细胞电活动模型。
