Esquerda J E, Solsona C, Marsal J
Neuroscience. 1982 Mar;7(3):751-8. doi: 10.1016/0306-4522(82)90080-x.
Isolated pure cholinergic synaptosomes from Torpedo electric organ were incubated in vitro with beta-bungarotoxin for 15, 30 and 60 min and processed for electron microscopy. It was found that no morphological damage was seen after 15 min but by contrast, severe disruption of synaptosomes was present at 30 or 60 min after incubation with toxin. Synaptosomes were incubated also for 15 min in the presence of 125I-labelled beta-bungarotoxin and the binding was evaluated by electron microscopic autoradiography. The toxin was found to bind to the presynaptic membrane. The surface density of toxin binding sites was calculated to be around 3000/micron2. In a minor population of synaptosomes, the toxin was translocated into large vesicles suggesting that the toxin-receptor complexes underwent endocytosis in such vesicles. These results give further support to the view that inhibition of transmitter release by the toxin is produced by its action on plasma membrane.
将从电鳐电器官分离出的纯胆碱能突触体在体外与β-银环蛇毒素一起孵育15、30和60分钟，然后进行电子显微镜处理。结果发现，孵育15分钟后未观察到形态损伤，但相比之下，与毒素孵育30或60分钟后突触体出现严重破坏。突触体也在125I标记的β-银环蛇毒素存在下孵育15分钟，并通过电子显微镜放射自显影评估结合情况。发现毒素与突触前膜结合。毒素结合位点的表面密度计算约为3000/μm²。在一小部分突触体中，毒素转移到大型囊泡中，表明毒素-受体复合物在这些囊泡中发生了内吞作用。这些结果进一步支持了毒素对递质释放的抑制作用是由其对质膜的作用所产生的这一观点。
