Study of the functional communication of α-and β-cells in pancreatic islets

本研究旨在研究在活的胰岛中不同种类的细胞，如α-、β-和δ-细胞，以类似于在分离的细胞条件下的方式响应。此外，还研究了胰岛中b细胞与b细胞之间的通讯。在本研究中，我们使用大鼠和小鼠的整个胰岛而不是胰腺组织切片来获得多细胞制剂，并将膜片钳技术应用于胰岛中的单细胞。根据Gopel等人的研究，通过获得特定细胞的电特性来进行细胞的鉴定。（J. Physiology，1999; 2000）。从我们的实验中，我们获得了以下结论：1）在胰岛β细胞中，葡萄糖刺激可引起动作电位的重复性爆发性放电，而在分离的胰岛β细胞中未观察到这种振荡性放电。2）Ca ^2+诱导的K^+电流在胰岛β细胞动作电位的终止中起作用。3）在胰岛中，相邻的β细胞与电导约为1 ns的差距连接电连通。4）α细胞和δ细胞具有不同的电特性，它们对葡萄糖刺激的反应机制也不同。5）胰岛中的β细胞表现出比分离的细胞大得多的胞吐能力，并且该作用至少部分地由从位于β细胞附近的α细胞释放的胰高血糖素介导。此外，我们发现完整β细胞的动力学是由单个β细胞中的混沌动力学耦合而成的，混沌可以作为胰腺β细胞不稳定性的一个指标。

This study was designed for investigating that in living islets different kinds of cells, such as α-, β-and δ-cells respond in a similar manner to that in isolated cellular condition. Further, the communication between b-cell to b-cell in islets was also investigated. In the present study, we used whole islets of the rat and mouse instead of slices of pancreatic tissue for obtaining multicellular preparations, and applied the patch-clamp technique to single cells in the islet Identification of cells was carried out by obtaining electrical characteristics of the particular cell, according to Gopel et al. (J. Physiology, 1999; 2000).From our experiments, we obtained the following condusions:1) In β-cells reside in intact islets, repetitive burst patterns of action potential firings appear in response to the glucose stimulation, while such a oscillatory response is not observed in isolated β-cells.2) K^+-currents induced by Ca^<2+> play a role for the termination of the action potentials of β-cells.3) In islets, adjoining β-cells are electrically communicated with the gap junction whose conductance is about 1 nS.4) a-cells and δ-cells have different electrical properties, and the mechanisms of theses cells for responding glucose stimulation are also different5) β-cell in islets exhibit an exocytotic capacity much larger than isolated cells, and this effect is mediated at least in part by glucagon released from a-cells residing near the β-cells. Further, we found that the dynamics of intact β-cells is constructed with coupling of individual chaotic dynamics in single β-cells, and chaos can be an index of instability in pancreatic β-cells.