Facilitation of quantal release induced by a D1-like receptor on bovine chromaffin cells.
Facilitation of quantal release induced by a D1-like receptor on bovine chromaffin cells.
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DOI：
10.1021/bi602661p
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发表时间：
2007-03
期刊：
影响因子：
2.9
通讯作者：
Melissa Villanueva;R. Wightman
中科院分区：
文献类型：
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作者：
Melissa Villanueva;R. Wightman
多巴胺能受体存在于牛肾上腺嗜铬细胞上，并且与促进可增强释放的内向钙电流有关[Artalejo 等人，(1990) Nature 348, 239-242]。然而，之前使用多巴胺能受体拮抗剂长时间（分钟）孵育的研究发现，儿茶酚胺释放受到抑制。在这项工作中，我们使用短暂（亚秒）化学去极化刺激来重新检查多巴胺能受体对牛肾上腺嗜铬细胞胞吐作用的作用。使用电流分析法来监测囊泡释放事件，并使用细胞内 fura-2 来检查单个细胞内的 Ca2+ 动态，从而比较对连续去极化刺激的反应。研究发现，暴露于 60 mM K+ 后，细胞内 Ca2+ 水平恢复至初始值的时间会延长，除非暴露时间很短（0.5 秒）并且细胞维持在 37 摄氏度。然而，在这些最佳条件下，第二次刺激比第一次诱发更多的胞吐事件。这种作用可以被 D1 拮抗剂 SCH-23390 以剂量依赖性方式阻断，但不能被 D2 拮抗剂雷氯必利阻断。 D1 激动剂 SKF-38393 与细胞先前暴露于肾上腺素一样，增加了胞吐事件的数量。综上所述，数据表明，释放的儿茶酚胺可以通过与牛肾上腺嗜铬细胞上的 D1 样受体相互作用来增强其自身释放。
Dopaminergic receptors are found on bovine adrenal chromaffin cells and have been implicated in the facilitation of an inward calcium current [Artalejo et al., (1990) Nature 348, 239-242] that could enhance release. However, previous studies using incubations of long duration (minutes) with dopaminergic receptor antagonists have found instead an inhibition of catecholamine release. In this work we used brief (subsecond) chemical depolarizing stimuli to reexamine the role of dopaminergic receptors on exocytosis from bovine adrenal chromaffin cells. Responses to consecutive depolarizing stimuli were compared using amperometry to monitor vesicular release events and intracellular fura-2 to examine Ca2+ dynamics within individual cells. Restoration of intracellular Ca2+ levels to their initial values following exposure to 60 mM K+ was found to be prolonged unless the exposure was brief (0.5 s) and the cells were maintained at 37 degrees C. However, with these optimum conditions, a second stimulation evoked more exocytotic events than the first. This effect was blocked by SCH-23390, a D1 antagonist, in a dose dependent fashion, but not by raclopride, a D2 antagonist. The D1 agonist, SKF-38393, enhanced the number of exocytotic events as did prior exposure of the cell to epinephrine. Taken together, the data indicate that released catecholamines can enhance their own release by interaction with a D1-like receptor on bovine adrenal chromaffin cells.