Electron microscope observations on compounds 48-80-induced degranulation in rat mast cells. Evidence for sequential exocytosis of storage granules.
Electron microscope observations on compounds 48-80-induced degranulation in rat mast cells. Evidence for sequential exocytosis of storage granules.
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DOI：
10.1083/jcb.51.2.465
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发表时间：
1971-11
期刊：
影响因子：
--
通讯作者：
Uvnäs B
中科院分区：
文献类型：
--
作者：
Röhlich P;Anderson P;Uvnäs B
在加入组胺解除剂化合物48/80(0.4µg/ml，17℃)后，在不同的时间间隔(10~60s)对大鼠肥大细胞的体外脱颗粒进行了研究。用电子显微镜观察超微结构变化，平行测定组胺释放量。此外，细胞外示踪剂镧和血红蛋白(由其过氧化活性证明)被应用于肥大细胞，以跟踪细胞外空间与脱颗粒过程中形成的空洞的联系。在10秒的滞后期后，位于最外围的颗粒开始脱颗粒。肾周膜与质膜融合，形成一个由薄横隔膜连接的孔。紧随其后的是隔膜破裂和颗粒基质挤出(胞吐)。这一过程通过较深位置的颗粒与先前开放的颗粒腔的融合和开放而向细胞内部推进。在这一过程结束时，细胞被一个复杂的空洞系统填满，其中包含许多变化的颗粒。细胞外示踪表明，这些细胞内腔从形成之初就与细胞外空间保持着不间断的联系。发现镧和血红蛋白都被吸附到腔的界膜上，并结合到改变的肥大细胞颗粒上。相反，不脱颗粒的肥大细胞中不存在示踪物质。化合物48/80对肥大细胞的脱颗粒作用被认为是一种连续的胞吐作用，这一过程类似于对某些外分泌腺细胞的描述。所有脱颗粒形成的“细胞内”空腔都与细胞外空间连通，因此，这些空腔中的颗粒必须被认为是生物细胞外的。目前的发现支持这样的观点，即组胺是由细胞外离子环境从颗粒基质释放出来的。
In vitro degranulation of rat mast cells was studied at different intervals ranging from 10 to 60 sec after adding the histamine liberator, compound 48/80 (0.4 µg/ml, 17°C). The ultrastructural changes were followed by electron microscopy, and parallel assays were made to determine the histamine released. In addition, the extracellular tracers lanthanum and hemoglobin (demonstrated by its peroxidative activity) were applied to mast cells to follow communication of the extracellular space with the cavities formed during degranulation. After a lag period of 10 sec, degranulation started in the most peripherally located granules. The perigranular membrane fused with the plasma membrane, resulting in a pore bridged by a thin diaphragm. This was followed by rupture of the diaphragm and extrusion of the granule matrix (exocytosis). The process advanced towards the cell interior by fusion and opening of the deeper situated granules to the formerly opened granule cavities. At the end of the process, the cell was filled by a system of complicated cavities containing a number of altered granules. Extracellular tracers have shown that these intracellular cavities were in unbroken communication with the extracellular space from the very beginning of their formation. Both lanthanum and hemoglobin were found to be adsorbed to the limiting membrane of the cavities and bound to altered mast cell granules. In contrast, no tracer substance was present in nondegranulating mast cells. Degranulation of mast cells by compound 48/80 is regarded as a sequential exocytosis, a process similar to that described for some exocrine gland cells. All the "intracellular" cavities, formed by degranulation, were shown to communicate with the extracellular space; consequently, granules lying in these cavities must be considered as biologically extracellular. The present findings support the view that histamine is released from the granule matrix by the extracellular ionic milieu.