Meda P, Atwater I, Gonçalves A, Bangham A, Orci L, Rojas E
Q J Exp Physiol. 1984 Oct;69(4):719-35.
beta-Cells in microdissected islets of Langerhans produce rhythmical bursts of electrical activity. This was monitored with two micro-electrodes simultaneously and the frequency and phase (collectively referred to as synchrony) of the two signals was investigated. At any instant two impaled cells produced bursts of the same frequency even when separated by up to 400 micron. When the electrode tips were separated by less than about 20 micron and current injection showed the cells to be ionically coupled the two signals were in phase and had almost identical shape. The phase relations between cells further apart were variable, the leading cell usually being located deeper within the islet than the other impaled cell. Increasing the glucose concentration increased electrical activity, reduced any phase lags and made the shape of the bursts more similar. There was less lag between the responses from two cells when the glucose concentration was suddenly reduced, than when it was suddenly increased. Qualitatively similar observations were made in glibenclamide-treated mice, a treatment previously shown to increase dye coupling between islet cells. However, the response to increasing glucose concentrations showed less phase lag; likewise the phase lag between bursts was reduced. Furthermore the response to current injected into one cell could be detected at much larger distances (up to 80 micron) than in control islets. This suggests that electrical coupling of beta-cells was improved in sulphonylurea-treated mice. Electron microscopy of both control and glibenclamide-treated mouse islets fixed at the end of each electrophysiological experiment showed the region impaled by the electrodes to be well preserved and, whenever the electrodes penetrated at least 20 micron into the islet, to contain a large proportion of beta-cells. The data support the view that, within an islet, most but not necessarily all cells are electrically synchronized, and that the coupling can be modulated by natural and pharmacological secretagogues.
在显微解剖的胰岛中的β细胞会产生有节律的电活动脉冲。使用两个微电极同时对此进行监测，并研究两个信号的频率和相位（统称为同步性）。在任何时刻，即使两个刺入的细胞相隔多达400微米，它们也会产生相同频率的脉冲。当电极尖端相隔小于约20微米且电流注入显示细胞存在离子偶联时，两个信号同相且形状几乎相同。相隔更远的细胞之间的相位关系是可变的，领先的细胞通常比另一个刺入的细胞位于胰岛内更深的位置。增加葡萄糖浓度会增加电活动，减少任何相位滞后，并使脉冲形状更相似。当葡萄糖浓度突然降低时，两个细胞反应之间的滞后比突然升高时要小。在格列本脲处理的小鼠中进行了定性相似的观察，先前的研究表明这种处理会增加胰岛细胞之间的染料偶联。然而，对葡萄糖浓度增加的反应显示出更小的相位滞后；同样，脉冲之间的相位滞后也减小了。此外，与对照胰岛相比，在距离注入电流的细胞更远的距离（高达80微米）处就能检测到对注入电流的反应。这表明在磺酰脲处理的小鼠中β细胞的电偶联得到了改善。在每个电生理实验结束时固定的对照和格列本脲处理的小鼠胰岛的电子显微镜检查显示，电极刺入的区域保存良好，并且只要电极至少刺入胰岛20微米，该区域就包含很大比例的β细胞。这些数据支持这样一种观点，即在一个胰岛内，大多数但不一定是所有细胞都电同步，并且这种偶联可以被天然和药理学促分泌剂调节。
