Gilon P, Shepherd R M, Henquin J C
Unité d'Endocrinologie et Métabolisme, University of Louvain Faculty of Medicine, Brussels, Belgium.
J Biol Chem. 1993 Oct 25;268(30):22265-8.
It is often assumed, but has not been demonstrated, that the oscillations of cytoplasmic calcium (Ca2+i) that occur in various secretory cells induce oscillations in secretion. Here, we have used single pancreatic islets from normal mice to monitor simultaneously insulin release and Ca2+i in beta-cells for periods up to 25 min. Ca2+i and insulin secretion were found to oscillate in synchrony during stimulation by glucose. This synchrony persisted when the frequency of both events changed spontaneously or upon addition of the hypoglycaemic sulfonylurea tolbutamide, or when their relative amplitudes varied. Repolarizing the beta-cell membrane with diazoxide abolished both Ca2+i and insulin oscillations. In contrast, epinephrine suppressed insulin oscillations in spite of the persistence of Ca2+i oscillations. This study is the first direct demonstration that, in an intact organ, sustained oscillations of Ca2+i induced by a physiological stimulus entrain synchronous oscillations of the functional response, and that both events can vary simultaneously or be dissociated depending on the experimental conditions.
人们常常假定，但尚未得到证实，即各种分泌细胞中发生的细胞质钙（Ca2+ i）振荡会诱导分泌振荡。在这里，我们使用来自正常小鼠的单个胰岛，在长达25分钟的时间内同时监测β细胞中的胰岛素释放和Ca2+ i。发现在葡萄糖刺激期间，Ca2+ i和胰岛素分泌同步振荡。当这两个事件的频率自发改变或加入降血糖磺脲类药物甲苯磺丁脲时，或者当它们的相对幅度变化时，这种同步性持续存在。用二氮嗪使β细胞膜复极化消除了Ca2+ i和胰岛素振荡。相反，尽管Ca2+ i振荡持续存在，肾上腺素仍抑制胰岛素振荡。这项研究首次直接证明，在完整器官中，生理刺激诱导的Ca2+ i持续振荡会带动功能反应的同步振荡，并且这两个事件可以根据实验条件同时变化或分离。
