3 TYPES OF CA2+ CHANNEL TRIGGER SECRETION WITH DIFFERENT EFFICACIES IN CHROMAFFIN CELLS
3 TYPES OF CA2+ CHANNEL TRIGGER SECRETION WITH DIFFERENT EFFICACIES IN CHROMAFFIN CELLS
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DOI：
10.1038/367072a0
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发表时间：
1994-01-06
期刊：
影响因子：
64.8
通讯作者：
FOX, AP
中科院分区：
文献类型：
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作者：
ARTALEJO, CR;ADAMS, ME;FOX, AP
为了确定是否存在于同一分泌细胞中的不同类型的Ca 2+通道同样有助于分泌，我们使用嗜铬细胞来分析三种不同类型的Ca 2+通道1和胞吐2，3之间的耦合。 这些是ω-芋螺毒素-GVIA敏感的4，5 N型通道，ω-龙舌兰毒素-IVA敏感的P型Ca 2+通道6和二氢吡啶敏感的易化Ca 2+通道，它们通常是静止的，但被去极化前脉冲激活，重复去极化到生理电位7，8，或提高环AMP的试剂9。我们同时监测了电容的变化，作为儿茶酚胺分泌10和Ca 2+电流的测定。虽然所有三种类型的Ca 2+通道单独触发分泌，但对于给定大小的Ca 2+电流，易化通道产生更大的分泌，表明它们更有效地与胞吐作用偶联。这些结果表明，便利化的Ca 2+通道可能是物理上更接近囊泡释放位点。他们还表明，低效率的P型和N型通道可以触发温和的释放，而高效率的易化通道可能是在“战斗或逃跑”反应期间发生的大量儿茶酚胺释放的基础。
To determine whether the different types of Ca2+ channels present in the same secretory cell contribute equally to secretion, we used chromaffin cells to analyse the coupling between three distinct types of Ca2+ channel1 and exocytosis2,3. These are omega-conotoxin-GVIA-sensitive4,5 N-type channels, omega-agatoxin-IVA-sensitive P-type Ca2+ channels6 and dihydropyridine-sensitive facilitation Ca2+ channels, which are normally quiescent but are activated by depolarizing pre-pulses, repetitive depolarizations to physiological potentials7,8, or agents that raise cyclic AMP9. We have simultaneously monitored changes in capacitance as an assay of catecholamine secretion10, and Ca2+ currents. Although all three types of Ca2+ channel trigger secretion individually, facilitation channels produce much greater secretion for a given size of Ca2+ current, indicating that they are coupled more efficiently to exocytosis. These results indicate that facilitation Ca2+ channels may be physically nearer vesicle release sites. They also show that low efficiency P- and N-type channels could trigger mild release and that high-efficiency facilitation channels may underlie the massive catecholamine release that occurs during the 'fight or flight' response.