Freeze-fracture studies of frog neuromuscular junctions during intense release of neurotransmitter. II. Effects of electrical stimulation and high potassium.
Freeze-fracture studies of frog neuromuscular junctions during intense release of neurotransmitter. II. Effects of electrical stimulation and high potassium.
复制标题
冻结神经肌肉连接的冻结裂纹研究在强烈释放神经递质时。 ii。电刺激和高钾的影响。
DOI：
10.1083/jcb.81.1.178
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发表时间：
1979-04
影响因子：
7.8
通讯作者：
Hurlbut, W P
中科院分区：
文献类型：
--
作者：
Ceccarelli, B;Grohovaz, F;Hurlbut, W P
在以下条件下通过冷冻断裂技术研究青蛙皮肤胸神经肌肉制剂：(a)重复间接刺激20分钟，10次/秒； (b) 从这种刺激中恢复期间； (c) 用 20 mM K+ 治疗期间。间接刺激使神经末梢突触前膜上出现许多凹坑或突起，且大多位于活动区附近。轴膜的深层内皱经常出现在活动区之间。在恢复的第一分钟内，凹痕、突起和内皱的数量和分布都没有明显变化。恢复 10 分钟后，凹痕、突起和内皱的数量大大减少。由于内吞作用在恢复期间剧烈进行，因此我们得出结论，内吞作用主要发生在靠近胞吐作用部位的活性区。 20 mM K+ 还会导致神经末梢轴膜上出现许多凹坑或突起，但它们沿着突触前膜几乎均匀分布。辣根过氧化物酶 (HRP) 实验表明，突触小泡的回收发生在 20 mM K+ 中。这种回收并不伴随着包被囊泡数量的变化。由于胞吐作用和内吞作用都发生在 20 mM K+ 中，因此很难解释这种独特的分布。然而，我们认为 K+ 会导致活性区域之间出现凹坑或突起，因为它激活了由位于活性区域之间的少量大膜内颗粒指定的潜在胞吐作用位点。潜在释放位点的激活可能与 K+ 对神经递质量子释放的复杂影响有关。
Frog cutaneous pectoris nerve muscle preparations were studied by the freeze-fracture technique under the following conditions: (a) during repetitive indirect stimulation for 20 min, 10/s; (b) during recovery from this stimulation; and (c) during treatment with 20 mM K+. Indirect stimulation causes numerous dimples or protuberances to appear on the presynaptic membrane of nerve terminal, and most are located near the active zones. Deep infoldings of the axolemma often develop between the active zones. Neither the number nor the distribution of dimples, protuberances, of infoldings changes markedly during the first minute of recovery. The number of dimples, protuberances, and infoldings is greatly reduced after 10 min of recovery. Since endocytosis proceeds vigorously during the recovery periods, we conclude that endocytosis occurs mostly at the active zones, close to the sites of exocytosis. 20 mM K+ also causes many dimples or protuberances to appear on the axolemma of the nerve terminal but they are distributed almost uniformly along the presynaptic membrane. Experiments with horseradish peroxidase (HRP) show that recycling of synaptic vesicles occurs in 20 mM K+. This recycling is not accompanied by changes in the number of coated vesicles. Since both exocytosis and endocytosis occur in 20 mM K+, it is difficult to account for this unique distribution. However, we suggest that K+ causes dimples or protuberances to appear between the active zones because it activates latent sites of exocytosis specified by small numbers of large intramembrane particles located between active zones. The activation of latent release sites may be related to the complex effects that K+ has on the quantal release of neurotransmitter.