Vautrin J, Kriebel M E, Holsapple J
Department of Physiology, SUNY Health Science Center, Syracuse.
J Neurosci Res. 1992 Jun;32(2):245-54. doi: 10.1002/jnr.490320214.
Fatt and Katz (Nature 166:597-598, 1950; J Physiol 117:109-128, 1952) attributed miniature endplate potentials (MEPPs) to the action of a standard quantity of transmitter, the quantum (Del Castillo and Katz, J Physiol 124:560-573, 1954). Quantal packets of transmitter were proposed to be preformed (Del Castillo and Katz, In CNRS Paris (Ed): "Microphysiologie comparée des éléments excitables" 67:245-258, 1957) and stored in large numbers in the motor nerve terminal. Statistical analyses of intervals between MEPPs and numbers of quanta composing small endplate potentials indicated that quantal release was a random process and that release sites functioned independently of each other. With the discovery of synaptic vesicles it was proposed that each contained one quantum of transmitter. The quantal-vesicular hypothesis (Del Castillo and Katz, as cited above) fails, however, to explain amplitude distributions of MEPPs that are skewed and/or that show multiple peaks (Kriebel et al., Brain Res Review 15:167-178, 1990). The drop formation process (Shaw, "The Dripping Faucet as a Model Chaotic System," Santa Cruz, CA: Aerial Press, Inc., 1984) was shown to generate amplitude classes of drops that were similar to classes of MEPPs which suggested that rapid changes in quantal size and ratios of skew- to bell-MEPPs could be explained with a simple dynamic process which determines quantal size at the moment of release (Kriebel et al., as cited above, 1990). Further similarities between miniature endplate currents (MEPCs) and the formation of drops are reported here. We found that rapid changes in MEPC amplitudes and time courses, which accompany an increase in frequency, mimic changes in drop sizes that accompany increases in flow rate. MEPC intervals have a minimum and their distributions are comparable to those of drop intervals. During an increased rate of transmitter release, MEPP amplitudes and intervals were positively correlated. The results suggest that spontaneously released transmitter "packets" are formed at the moment of release and that transmitter supply to the process that forms packets is continuous.
法特和卡茨（《自然》166:597 - 598，1950年；《生理学杂志》117:109 - 128，1952年）将微小终板电位（MEPPs）归因于标准量递质——量子的作用（德尔卡斯蒂略和卡茨，《生理学杂志》124:560 - 573，1954年）。有人提出递质的量子包是预先形成的（德尔卡斯蒂略和卡茨，载于法国国家科学研究中心巴黎编：《可兴奋元件的比较微生理学》67:245 - 258，1957年），并大量储存在运动神经末梢中。对MEPPs之间的间隔以及构成小终板电位的量子数量的统计分析表明，量子释放是一个随机过程，且释放位点彼此独立起作用。随着突触小泡的发现，有人提出每个突触小泡含有一个量子的递质。然而，量子 - 小泡假说（德尔卡斯蒂略和卡茨，如前所述）无法解释呈偏态分布和/或显示多个峰值的MEPPs的幅度分布（克里布尔等人，《脑研究回顾》15:167 - 178，1990年）。液滴形成过程（肖，《作为模型混沌系统的滴水水龙头》，加利福尼亚州圣克鲁斯：空中出版社，1984年）被证明能产生与MEPPs类别相似的液滴幅度类别，这表明量子大小的快速变化以及偏态MEPPs与钟形MEPPs的比例可以用一个简单的动态过程来解释，该过程在释放瞬间决定量子大小（克里布尔等人，如前所述，1990年）。本文报道了微小终板电流（MEPCs）与液滴形成之间的进一步相似之处。我们发现，随着频率增加，MEPC幅度和时间过程的快速变化类似于随着流速增加液滴大小的变化。MEPC间隔有一个最小值，其分布与液滴间隔的分布相当。在递质释放速率增加期间，MEPP幅度和间隔呈正相关。结果表明，自发释放的递质“包”在释放瞬间形成，并且向形成包的过程的递质供应是连续的。
