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首页> 外文期刊>The European Journal of Neuroscience >Calcium dynamics in bovine adrenal medulla chromaffin cell secretory granules.
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Calcium dynamics in bovine adrenal medulla chromaffin cell secretory granules.

机译：牛肾上腺髓质嗜铬细胞分泌颗粒中的钙动力学。

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The secretory granules constitute one of the less well-known compartments in terms of Ca2+ dynamics. They contain large amounts of total Ca2+, but the free intragranular [Ca2+] ([Ca2+]SG), the mechanisms for Ca2+ uptake and release from the granules and their physiological significance regarding exocytosis are still matters of debate. We used in the present work an aequorin chimera targeted to the granules to investigate [Ca2+]SG homeostasis in bovine adrenal chromaffin cells. We found that most of the intracellular aequorin chimera is present in a compartment with 50-100 microM Ca2+. Ca2+ accumulation into this compartment takes place mainly through an ATP-dependent mechanism, namely, a thapsigargin-sensitive Ca2+-ATPase. In addition, fast Ca2+ release was observed in permeabilized cells after addition of inositol 1,4,5-trisphosphate (InsP3) or caffeine, suggesting the presence of InsP3 and ryanodine receptors in the vesicular membrane. Stimulation of intact cells with the InsP3-producing agonist histamine or with caffeine also induced Ca2+ release from the vesicles, whereas acetylcholine or high-[K+] depolarization induced biphasic changes in vesicular[Ca2+], suggesting heterogeneous responses of different vesicle populations, some of them releasing and some taking up Ca2+during stimulation. In conclusion, our data show that chromaffin cell secretory granules have the machinery required for rapid uptake and release of Ca2+, and this strongly supports the hypothesis that granular Ca2+ may contribute to its own secretion.
机译：就Ca 2+动力学而言，分泌颗粒构成了鲜为人知的隔室之一。它们包含大量的总Ca2 +，但是游离的颗粒内[Ca2 +]（[Ca2 +] SG），Ca2 +从颗粒中吸收和释放的机制以及它们对胞吐作用的生理意义仍然是有争议的问题。在目前的工作中，我们使用了针对颗粒的水母发光蛋白嵌合体，以研究牛肾上腺嗜铬细胞中的[Ca2 +] SG稳态。我们发现大多数细胞内水母发光蛋白嵌合体存在于具有50-100 microM Ca2 +的隔室中。 Ca2 +积累到该区室中的过程主要是通过ATP依赖的机制进行的，即毒胡萝卜素敏感的Ca2 + -ATPase。此外，在加入肌醇1,4,5-三磷酸酯（InsP3）或咖啡因后，通透性细胞中Ca2 +的释放迅速，这提示水泡膜中存在InsP3和ryanodine受体。用产生InsP3的激动剂组胺或咖啡因刺激完整细胞也可诱导小泡中Ca2 +的释放，而乙酰胆碱或高[K +]去极化可引起小泡中的两相性变化[Ca2 +]，表明不同小泡群体的异质性反应，其中一些它们释放并在刺激过程中吸收钙+。总之，我们的数据表明，嗜铬细胞分泌颗粒具有快速摄取和释放Ca2 +所需的机制，这有力地支持了Ca2 +颗粒可能有助于其自身分泌的假设。

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