HISTAMINE RELEASE FROM BEIGE MOUSE MAST CELLS

米色小鼠的肥大细胞含有大量的细胞内分泌物 颗粒(直径约4微米)，其膜与 质膜在一种称为胞吐作用的过程中。在膜融合过程中 一个胞吐的小孔形成，它连接颗粒内部和 胞外培养液。通过胞吐毛孔，颗粒内容物 释放到细胞外，可以自由扩散到靶细胞。 我们已经将电生理和光学显微镜数据与 观察肥大细胞分泌过程中胞吐毛孔的结构 米色小鼠的细胞。毛孔扩张的时间进程为 高度可变：它可以快速或缓慢地扩大，并可以在 可变电导的扩张和收缩状态(闪烁)。首字母 孔隙大小分布广泛，表明这个孔隙是不同的 从传统的膜通道有一个相对固定的 电导。给定孔的出现频率直方图 电导很宽，主峰在1到4 ns之间，表明 这种孔的大小并不是以量子步长增加的。次极大值 发生在北纬30度左右。我们搜索了快速冷冻的冰冻骨折 大鼠肥大细胞的复制品，并识别出具有小腔的毛孔。30岁的 NS孔可能是透射式电子中最小的孔。 显微镜。一个在分子水平上描述融合的模型，它可以 解释了不同的孔大小、闪烁和已知体积 对激活进行了描述。 在第二个项目中，巨型分泌囊泡的分离基质 对米色小鼠肥大细胞进行检测，以确定离子对 洗澡液的组成取决于它们的大小。一般说来，多价 相对于一价键，阳离子使基质缩合。

Mast cells of the beige mouse contain large intracellular secretory granules (approximately 4 microns in diameter) whose membranes fuse with the plasma membrane in a process called exocytosis. During membrane fusion an exocytotic pore forms which connects the granule interior with the extracellular medium. Through the exocytotic pore the granule contents are released extracellularly and are free to diffuse to target cells. We have correlated electrophysiological and light microscopic data to investigate the structure of this exocytotic pore during secretion in mast cells from Beige mice. The time course for the widening of the pore is highly variable: it can widen quickly or slowly and can fluctuate between dilated and contracted states of variable conductance (flickering). Initial pore sizes are broadly distributed indicating that this pore is different from traditional membrane channels which have a relatively fixed conductance. The frequency histogram for occurrence of pores of given conductance is broad with a primary peak between 1 and 4 nS, indicating that pore size does not increase in quantal steps. A secondary maximum occurs at about 30 nS. We have searched fast-frozen, freeze-fracture replicas of rat mast cells and identified pores with small lumens. The 30 nS pores may represent the smallest pores seen in transmission electron microscopy. A model describing fusion on the molecular level which can account for the variable pore sizes, flickering, and known volumes of activation is described. In a second project isolated matrices of the giant secretory vesicles of Beige mouse mast cells were examined to determine the effects of the ionic composition of the bathing solution on their size. In general multivalent cations condense the matrix relative to univalents.