Elhamdani A, Palfrey H C, Artalejo C R
Department of Pharmacology, Wayne State University School of Medicine, Detroit, MI 48201, USA.
Neuron. 2001 Sep 13;31(5):819-30. doi: 10.1016/s0896-6273(01)00418-4.
To what extent the quantal hypothesis of transmitter release applies to dense-core vesicle (DCV) secretion is unknown. We determined the characteristics of individual secretory events in calf chromaffin cells using catecholamine amperometry combined with different patterns of stimulation. Raising the frequency of action potential trains from 0.25-10 Hz in 2 mM [Ca(2+)]o or [Ca(2+)]o from 0.25-7 mM at 7 Hz elevated the amount released per event (quantal size). With increased stimulation, quantal size rose continuously, not abruptly, suggesting that release efficiency from a single population of DCVs rather than recruitment of different-sized vesicles contributed to the effect. These results suggest that catecholamine secretion does not conform to the quantal model. Inhibition of rapid endocytosis damped secretion in successive episodes, implying an essential role for this process in the recycling of vesicles needed for continuous secretion.
递质释放的量子假说在多大程度上适用于致密核心囊泡（DCV）分泌尚不清楚。我们使用儿茶酚胺安培法结合不同的刺激模式，确定了小牛嗜铬细胞中单个分泌事件的特征。在2 mM [Ca(2+)]o中将动作电位串的频率从0.25 - 10 Hz提高，或在7 Hz时将[Ca(2+)]o从0.25 - 7 mM提高，均增加了每个事件的释放量（量子大小）。随着刺激增加，量子大小持续上升，而非突然上升，这表明来自单个DCV群体的释放效率而非不同大小囊泡的募集促成了这一效应。这些结果表明儿茶酚胺分泌不符合量子模型。快速内吞作用的抑制在连续发作中减弱了分泌，这意味着该过程在持续分泌所需囊泡的再循环中起重要作用。
