Golan H, Colton J S, Moore H J, Grossman Y
Department of Physiology, Corob Center for Medical Research, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel.
Pflugers Arch. 1995 Sep;430(5):617-25. doi: 10.1007/BF00386155.
The cellular mechanisms underlying the effect of high pressure on synaptic transmission were studied in the opener muscle of the lobster walking leg. Excitatory postsynaptic currents (EPSCs) were recorded using a loose macropatch-clamp technique at normal pressure and 3.5, 6.9 MPa helium pressure. Responses of the single excitatory axon could be grouped into two types: low-yield (L) synapses exhibiting small EPSCs with a considerable number of failures, and high-yield (H) synapses having larger EPSCs with very few failures. High pressure reduced the average EPSC amplitude in all synapses and shifted their amplitude histograms to the left by decreasing the quantal content (m) without changing their quantum current (q). A binomial distribution fit of EPSC amplitudes revealed that high pressure greatly decreased n, the number of available active zones, but the effect on p, the probability of release for each zone, was not consistent. Many of the spontaneous miniature EPSCs (mEPSCs), observed only in L-type synapses, were "giant" (size = 2-5 q). High pressure increased the frequency of the giant mEPSCs but had little effect on their amplitude histogram. High pressure depressed evoked synaptic transmission by modulating the presynaptic quantal release parameters, but concomitantly enhanced spontaneous quantal release by an unknown mechanism.
在龙虾步行腿的 opener 肌肉中研究了高压对突触传递影响的细胞机制。使用松散的膜片钳技术在常压和 3.5、6.9 MPa 氦压下记录兴奋性突触后电流（EPSC）。单个兴奋性轴突的反应可分为两种类型：低产量（L）突触，表现为小的 EPSC 且有相当数量的失败情况；高产量（H）突触，具有较大的 EPSC 且很少有失败情况。高压降低了所有突触中平均 EPSC 幅度，并通过降低量子含量（m）而不改变其量子电流（q）将其幅度直方图向左移动。EPSC 幅度的二项分布拟合显示，高压大大降低了可用活性区的数量 n，但对每个区的释放概率 p 的影响并不一致。仅在 L 型突触中观察到的许多自发微小 EPSC（mEPSC）是“巨大的”（大小 = 2 - 5q）。高压增加了巨大 mEPSC 的频率，但对其幅度直方图影响不大。高压通过调节突触前量子释放参数抑制诱发的突触传递，但同时通过未知机制增强了自发量子释放。
