Barg Sebastian, Olofsson Charlotta S, Schriever-Abeln Jenny, Wendt Anna, Gebre-Medhin Samuel, Renström Erik, Rorsman Patrik
Department of Molecular and Cellular Physiology, Institute for Physiological Sciences, Lund University, The Biomedical Center F11, Lund SE-221 84, Sweden.
Neuron. 2002 Jan 17;33(2):287-99. doi: 10.1016/s0896-6273(02)00563-9.
Peptidergic neurotransmission is slow compared to that mediated by classical neurotransmitters. We have studied exocytotic membrane fusion and cargo release by simultaneous capacitance measurements and confocal imaging of single secretory vesicles in neuroendocrine cells. Depletion of the readily releasable pool (RRP) correlated with exocytosis of 10%-20% of the docked vesicles. Some remaining vesicles became releasable after recovery of RRP. Expansion of the fusion pore, seen as an increase in luminal pH, occurred after approximately 0.3 s, and peptide release was delayed by another 1-10 s. We conclude that (1) RRP refilling involves chemical modification of vesicles already in place, (2) the release of large neuropeptides via the fusion pore is negligible and only proceeds after complete fusion, and (3) sluggish peptidergic transmission reflects the time course of vesicle emptying.
与经典神经递质介导的神经传递相比，肽能神经传递速度较慢。我们通过同时进行电容测量和对神经内分泌细胞中单个分泌囊泡的共聚焦成像，研究了胞吐性膜融合和货物释放过程。易释放池（RRP）的耗尽与停靠囊泡10%-20%的胞吐作用相关。RRP恢复后，一些剩余的囊泡变得可释放。融合孔的扩张表现为腔内pH值升高，大约在0.3秒后发生，而肽的释放又延迟了1-10秒。我们得出结论：（1）RRP的重新填充涉及对已就位囊泡的化学修饰；（2）通过融合孔释放大的神经肽可忽略不计，且仅在完全融合后才发生；（3）缓慢的肽能传递反映了囊泡排空的时间进程。
