An osmotic mechanism for exocytosis from dissociated chromaffin cells.
An osmotic mechanism for exocytosis from dissociated chromaffin cells.
复制标题
游离嗜铬细胞胞吐作用的渗透机制。
DOI：
10.1016/s0021-9258(17)43574-5
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发表时间：
1984
期刊：
影响因子：
--
通讯作者：
A. Hotchkiss
中科院分区：
文献类型：
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作者：
H. Pollard;C. Pazoles;C. Creutz;J. Scott;O. Zinder;A. Hotchkiss
在一项研究中，用各种促分泌素刺激牛肾上腺髓质的分离嗜铬细胞分泌肾上腺素和多巴胺β-羟化酶，以检验分离嗜铬颗粒的化学渗透溶解反应可能以某种方式与胞吐过程中的释放机制有关的假设。增加与NaCl或蔗糖的孵育介质的渗透强度导致抑制肾上腺素从细胞的分泌，无论分泌是否与藜芦碱或乙酰胆碱诱导。分泌抑制与渗透强度呈近似指数关系。只有当培养基中含有渗透性阴离子，如氯离子时，才会发生肾上腺素分泌，当羟乙基磺酸钠取代培养基中的NaCl时，由藜芦碱诱导的分泌被抑制。在一项广泛的研究与不同的单价阴离子藜芦碱支持肾上腺素分泌根据以下活动系列：Br-，I-，NO3-大于甲基硫酸盐，SCN-大于Cl大于乙酸盐远远大于羟乙基磺酸盐。用A23187作为激动剂，观察到类似的系列，除了NO3-的效力。一般来说，颗粒溶解的阴离子系列是类似的。然而，化学渗透颗粒溶解的阴离子依赖性和细胞分泌的阴离子依赖性之间的定量相关性较差。阴离子转运抑制剂，如丙磺舒和磷酸吡哆醛也抑制分泌，而二苯乙烯二磺酸盐无活性。二苯乙烯二磺酸盐的无效性进一步区分了细胞分泌的化学渗透颗粒溶解。当培养基中的NaCl被等渗蔗糖取代时，由藜芦碱或烟碱（一种胆碱能激动剂）诱导的儿茶酚胺分泌受到抑制，在某些情况下观察到出乎意料的低水平多巴胺β-羟化酶。总之，这些性质的分泌嗜铬细胞类似于一些性质的孤立的嗜铬颗粒孵育在ATP和Cl-，但在一些情况下是不同的。因此，我们已经解释了我们的数据表明，虽然一些机制的关系可能确实存在之间的释放事件从嗜铬细胞胞吐和化学渗透溶解反应的特点孤立的嗜铬颗粒，胞吐的能量学的理解等待发现的原因两个系统之间的定量差异。
Dissociated chromaffin cells from bovine adrenal medulla were stimulated to secrete epinephrine and dopamine beta-hydroxylase with a variety of secretagogues in a study designed to test the hypothesis that the chemiosmotic lysis reaction of isolated chromaffin granules might in some way be related to the mechanism of release during exocytosis. Increasing the osmotic strength of the incubation medium with either NaCl or sucrose led to suppression of secretion of epinephrine from the cells regardless of whether secretion was induced with veratridine or acetylcholine. Suppression of secretion was approximately exponential with respect to osmotic strength. Epinephrine secretion occurred only if the medium contained a permeant anion such as chloride, and secretion induced by veratridine was suppressed when Na isethionate replaced NaCl in the medium. In an extensive study with different monovalent anions veratridine supported epinephrine secretion according to the following activity series: Br-, I-, NO3- greater than methylsulfate, SCN- greater than Cl greater than acetate much greater than isethionate. A similar series, except for the potency of NO3-, was observed with A23187 as agonist. In general, the anion series for granule lysis was analogous. However, there was a poor quantitative correlation between the anion dependence of chemiosmotic granule lysis and the anion dependence of cell secretion. Anion transport inhibitors such as probenecid and pyridoxal phosphate also inhibited secretion while the stilbene disulfonates were inactive. The ineffectiveness of the stilbene disulfonates further distinguished chemiosmotic granule lysis from cell secretion. Secretion of catecholamines, induced by veratridine or nicotine, a cholinergic agonist, was suppressed when NaCl in the medium was replaced by isosmotic sucrose and unexpectedly low levels of dopamine beta-hydroxylase were observed in some cases. In sum, these properties of secreting chromaffin cells resembled some properties of isolated chromaffin granules incubated in ATP and Cl-, but were different in a number of instances. We, therefore, have interpreted our data to indicate that while some mechanistic relationships may indeed exist between the release event in exocytosis from chromaffin cells and the chemiosmotic lysis reaction characteristic of isolated chromaffin granules, an understanding of the energetics of exocytosis awaits the discovery of reasons for the quantitative differences between the two systems.