Gap junctions mediate electrical signaling and ensuing cytosolic Ca2+ increases between chromaffin cells in adrenal slices:: A role in catecholamine release
Gap junctions mediate electrical signaling and ensuing cytosolic Ca2+ increases between chromaffin cells in adrenal slices:: A role in catecholamine release
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DOI：
10.1523/jneurosci.21-15-05397.2001
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发表时间：
2001-08-01
影响因子：
5.3
通讯作者：
Guérineau, NC
中科院分区：
文献类型：
--
作者：
Martin, AO;Mathieu, MN;Guérineau, NC
在肾上腺嗜铬细胞中，胞浆钙浓度（[Ca 2 +]i）的升高是内脏神经激活后触发儿茶酚胺胞吐的关键事件。动作电位或尼古丁诱导的[Ca2+]i瞬变在单个嗜铬细胞中得到了很好的描述，但它们是否在空间上局限于受刺激的细胞或传播到相邻的细胞尚不清楚。为了解决这个问题，在大鼠急性肾上腺切片中使用膜片钳技术和实时共聚焦成像研究了嗜铬细胞之间的电和相关Ca2+事件的时空组织。自发或电诱发的动作电位驱动的[Ca2+]i瞬变同时检测到相邻的细胞。这可能归因于间隙连接介导的电紧张性通讯，如（1）细胞对之间监测的电压变化的双向反射，（2）表现出自发同步[Ca2+]i瞬变的细胞之间的荧光黄（LY）扩散，以及（3）使用解偶联剂甘珀酸减少LY扩散所示。此外，在单个嗜铬细胞中发现了编码两种连接蛋白（Cx36和Cx43）的转录本。这种间隙连接耦合激活后，突触样应用尼古丁介导的同步多细胞[Ca2+]i增加。此外，烟碱刺激一个单一的细胞触发儿茶酚胺释放耦合的细胞，所示的安培检测分泌事件。原位嗜铬细胞之间的功能耦合可能是对突触传递的有效补充，以放大单个兴奋嗜铬细胞突触刺激后的儿茶酚胺释放。
In adrenal chromaffin cells, a rise in cytosolic calcium concentration ([ Ca2+]i) is a key event in the triggering of catecholamine exocytosis after splanchnic nerve activation. Action potential-or nicotine-induced [Ca2+]i transients are well described in individual chromaffin cells, but whether they remain spatially confined to the stimulated cell or propagate to adjacent cells is not yet known. To address this issue, the spatiotemporal organization of electrical and associated Ca2+ events between chromaffin cells was investigated using the patch-clamp technique and real-time confocal imaging in rat acute adrenal slices. Spontaneous or electrically evoked action potential-driven [Ca2+]i transients were simultaneously detected in neighboring cells. This was likely attributable to gap junction-mediated electrotonic communication, as shown by (1) the bidirectional reflection of voltage changes monitored between cell pairs, (2) Lucifer yellow (LY) diffusion between cells exhibiting spontaneous synchronized [Ca2+]i transients, and (3) the reduction of LY diffusion using the uncoupling agent carbenoxolone. Furthermore, transcripts encoding two connexins (Cx36 and Cx43) were found in single chromaffin cells. This gap junctional coupling was activated after a synaptic-like application of nicotine that mediated synchronous multicellular [Ca2+]i increases. In addition, nicotinic stimulation of a single cell triggered catecholamine release in coupled cells, as shown by amperometric detection of secretory events. Functional coupling between chromaffin cells in situ may represent an efficient complement to synaptic transmission to amplify catecholamine release after synaptic stimulation of a single excited chromaffin cell.