Klyachko Vitaly A, Jackson Meyer B
Department of Physiology and Biophysics Graduate Program, University of Wisconsin-Madison, 1300 University Avenue, Madison, Wisconsin 53706, USA.
Nature. 2002 Jul 4;418(6893):89-92. doi: 10.1038/nature00852.
The vesicles that package neurotransmitters fall into two distinct classes, large dense-core vesicles (LDCVs) and small synaptic vesicles, the coexistence of which is widespread in nerve terminals. High resolution capacitance recording reveals unitary steps proportional to vesicle size. Measurements of capacitance steps during LDCV and secretory granule fusion in endocrine and immune cells have provided important insights into exocytosis; however, extending these measurements to small synaptic vesicles has proven difficult. Here we report single vesicle capacitance steps in posterior pituitary nerve terminals. These nerve terminals contain neuropeptide-laden LDCVs, as well as microvesicles. Microvesicles are similar to synaptic vesicles in size, morphology and molecular composition, but their contents are unknown. Capacitance steps of two characteristic sizes, corresponding with microvesicles and LDCVs, were detected in patches of nerve terminal membrane. Both types of vesicles fuse in response to depolarization-induced Ca(2+) entry. Both undergo a reversible fusion process commonly referred to as 'kiss-and-run', but only rarely. Fusion pores seen during microvesicle kiss-and-run have a conductance of 19 pS, 11 times smaller than LDCV fusion pores. Thus, LDCVs and microvesicles use structurally different intermediates during exocytosis.
包裹神经递质的囊泡可分为两类，即大的致密核心囊泡（LDCV）和小的突触囊泡，它们在神经末梢中普遍共存。高分辨率电容记录显示与囊泡大小成比例的单位阶跃。在内分泌和免疫细胞中对LDCV和分泌颗粒融合过程中的电容阶跃进行测量，为胞吐作用提供了重要见解；然而，将这些测量扩展到小的突触囊泡已被证明是困难的。在此，我们报告了垂体后叶神经末梢中的单个囊泡电容阶跃。这些神经末梢含有装载神经肽的LDCV以及微囊泡。微囊泡在大小、形态和分子组成上与突触囊泡相似，但其内容物未知。在神经末梢膜片上检测到了两种特征尺寸的电容阶跃，分别对应于微囊泡和LDCV。两种类型的囊泡都响应去极化诱导的Ca(2+)内流而融合。两者都经历一种通常称为“吻-跑”的可逆融合过程，但很少发生。微囊泡“吻-跑”过程中看到的融合孔电导为19 pS，比LDCV融合孔小11倍。因此，LDCV和微囊泡在胞吐作用过程中使用结构不同的中间体。
