RELATIONSHIP OF TRANSMITTER RELEASE AND STORAGE TO FINE-STRUCTURE IN A SYMPATHETIC-GANGLION
RELATIONSHIP OF TRANSMITTER RELEASE AND STORAGE TO FINE-STRUCTURE IN A SYMPATHETIC-GANGLION
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DOI：
10.1007/bf01098386
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发表时间：
1974-01-01
期刊：
影响因子：
--
通讯作者：
BIRKS, RI
中科院分区：
文献类型：
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作者：
BIRKS, RI
用戊二醛在Mg ~（++）存在下灌注固定猫交感神经节，制备电镜标本。在休息终扣去通道的突触囊泡的人口是6400每个终扣。囊泡的分布显示出许多紧密堆积的球体特征。基于囊泡紧密堆积假设的计算给出了每个钮扣8000个囊泡的数字。在神经节刺激20分钟，在20/s的囊泡人口减少到25%，和28.5%的神经节，其中乙酰胆碱（ACh）的合成被半胆碱（HC-3）抑制。当刺激1 min时，囊泡数量减少到34%。在1/s和4/s刺激20 min的神经节中，囊泡数量分别减少到44%和46%。即使在以4/s刺激1分钟后，超过一半的终扣显示囊泡的显著损失。已知除了在HC-3存在下的刺激外，神经节中的ACh储存不会被任何这些程序耗尽。已知通过以20/s或4/s刺激1分钟和以1/s刺激20分钟释放的神经节ACh储存的分数基本上小于囊泡损失的分数。因此，这些观察结果并不容易被递质储存和释放的囊泡理论所解释。他们是一致的想法，乙酰胆碱储存在小泡在休息，但在保持活动超过一半的布顿乙酰胆碱是游离在细胞质中。细胞质ACh的浓度计算为约50-150 mm 1−1。对突触激活过程中ACh可能从胞质池中释放的假设的检验表明，大约1.5-3.0 × 10− 12 M Ach cm− 2突触膜/冲动的流出量。
Cat sympathetic ganglia were prepared for electron microscopy by perfusion fixation with glutaraldehyde in the presence of Mg++. At resting boutons de passage the populations of synaptic vesicles were 6400 per bouton. The vesicle distributions displayed many of the features of spheres in close-packing. Calculations based on a vesicle close-packing hypothesis gave a figure of 8000 vesicles per bouton. In ganglia stimulated for 20 min at 20/s the vesicle populations were reduced to 25%, and to 28.5% in ganglia in which acetylcholine (ACh) synthesis was inhibited by hemicholinium (HC-3). The reduction was to 34% when stimulation was for 1 min. In ganglia stimulated for 20 min at 1/s and 4/s the vesicle populations were reduced to 44% and 46% respectively. Even following 1 min stimulation at 4/s over half the boutons showed significant loss of vesicles. ACh stores in ganglia are known not to be depleted by any of these procedures except stimulation in the presence of HC-3. The fraction of ganglionic ACh stores known to be released by stimulation for 1 min at 20/s or 4/s and by 20 min stimulation at 1/s is substantially less than the fraction of vesicles lost. The observations therefore were not readily accounted for by the vesicle theory of transmitter storage and release. They were consistent with the idea the ACh is stored in vesicles at rest, but that during maintained activity over half the bouton ACh is free in the cytoplasm. The concentration of cytoplasmic ACh was calculated to be approximately 50–150 mm 1−1. Examination of the hypothesis that ACh may be released from this cytoplasmic pool during synaptic activation indicated an efflux of approximately 1.5–3.0 × 10−12M Ach cm−2synapsing membrane/impulse.