Microfluidic alucose stimulation reveals limited coordination of intracellular Ca2+ activity oscillations in pancreatic islets
Microfluidic alucose stimulation reveals limited coordination of intracellular Ca2+ activity oscillations in pancreatic islets
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DOI：
10.1073/pnas.0405149101
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发表时间：
2004-08-31
影响因子：
11.1
通讯作者：
Piston, DW
中科院分区：
文献类型：
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作者：
Rocheleau, JV;Walker, GM;Piston, DW
胰岛是一个通过调节胰岛素和其他激素分泌来维持正常血糖的功能性微型器官。细胞外葡萄糖通过增加氧化还原状态刺激胰岛β细胞分泌胰岛素，这可以通过NAD(P)H自身荧光来测量。葡萄糖浓度超过约7毫米产生β细胞内Ca2+浓度（[Ca2+],）的同步振荡，导致搏动性胰岛素分泌。流行的模型假设胰岛作为一个功能性合胞体，整个胰岛[Ca2+](i)反应已经根据胰岛破裂和起搏器模型建模。为了测试这些模型，我们开发了一种微流体装置，能够部分刺激胰岛，同时允许观察NAD(P)H和[Ca2+](i)响应。我们表明β细胞[Ca2+](i)振荡只发生在超过约6.6 mM葡萄糖刺激的区域内。此外，我们发现，作为atp敏感的K+通道的拮抗剂，甲苯丁胺允许这些振荡进一步传播到胰岛的非刺激区域。我们的方法表明，Ca2+在胰岛上的传播程度取决于耦合程度和atp敏感的K+通道激活程度之间的微妙相互作用，并说明了一个将对许多其他生物系统有用的实验范例。
The pancreatic islet is a functional microorgan involved in maintaining normoglycemia through regulated secretion of insulin and other hormones. Extracellular glucose stimulates insulin secretion from islet beta cells through an increase in redox state, which can be measured by NAD(P)H autofluorescence. Glucose concentrations over approximate to7 mM generate synchronous oscillations in beta cell intracellular Ca2+ concentration ([Ca2+],), which lead to pulsatile insulin secretion. Prevailing models assume that the pancreatic islet acts as a functional syncytium, and the whole islet [Ca2+](i) response has been modeled in terms of islet bursting and pacemaker models. To test these models, we developed a microfluidic device capable of partially stimulating an islet, while allowing observation of the NAD(P)H and [Ca2+](i) responses. We show that beta cell [Ca2+](i) oscillations occur only within regions stimulated with more than approximate to6.6 mM glucose. Furthermore, we show that tolbutamide, an antagonist of the ATP-sensitive K+ channel, allows these oscillations to travel farther into the nonstimulated regions of the islet. Our approach shows that the extent of Ca2+ propagation across the islet depends on a delicate interaction between the degree of coupling and the extent of ATP-sensitive K+-channel activation and illustrates an experimental paradigm that will have utility for many other biological systems.