Creutz C E, Pollard H B
Biophys J. 1980 Aug;31(2):255-70. doi: 10.1016/S0006-3495(80)85055-7.
A model is constructed to describe the behavior of isolated chromaffin granules (secretory vesicles of the adrenal medulla) when they are induced to release their contents by incubation with MgATP and Cl-. The model is based on the assumption that the release event is osmotic lysis due to the ATPase dependent influx of protons and osmotically active Cl- ions. The consequences of this influx of osmotically active particles are predicted from osmotic fragility curves determined by suspending granules in hypotonic media. Turbidity measurements on granule suspensions undergoing the ATP and Cl- dependent release reaction are used to fit the parameters of the model. The model then successfully described the time course, Cl- dependence, ATP dependence, and osmotic strength suppression of the release event as monitored either by measurement of turbidity changes or of epinephrine release. The degree of suppression of release predicted in hypertonic media is also in agreement with published data on hypertonic suppression of exocytosis from several cell types: chromaffin cells, blood platelets, and parathyroid cells. Therefore, the model may also provide an accurate description of some of the events occurring during exocytosis.
构建了一个模型，用于描述分离的嗜铬颗粒（肾上腺髓质的分泌囊泡）在与MgATP和Cl-孵育诱导其释放内容物时的行为。该模型基于这样的假设：释放事件是由于ATP酶依赖的质子和具有渗透活性的Cl-离子流入导致的渗透裂解。通过将颗粒悬浮在低渗介质中测定的渗透脆性曲线来预测这种具有渗透活性的颗粒流入的后果。对经历ATP和Cl-依赖性释放反应的颗粒悬浮液进行浊度测量，以拟合模型参数。然后，该模型成功地描述了通过测量浊度变化或肾上腺素释放监测的释放事件的时间进程、对Cl-的依赖性、对ATP的依赖性以及渗透强度抑制。在高渗介质中预测的释放抑制程度也与关于几种细胞类型（嗜铬细胞、血小板和甲状旁腺细胞）胞吐作用的高渗抑制的已发表数据一致。因此，该模型也可能准确描述胞吐过程中发生的一些事件。
