权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Mechanisms of Transmitter Release : Ca-Dependent Release and Ca-Independent Release.

递质释放机制：Ca依赖性释放和Ca非依赖性释放。

基本信息

批准号：
63480111
负责人：
TACHIBANA Masao
金额：
$ 3.78万
依托单位：
The University of Tokyo (1989-1990)Okazaki National Research Institutes (1988)
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1988
资助国家：
日本
起止时间：
1988 至 1990
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-63480111/
关键词：
Retina Neuron Glia Synapse Chemical transmitter Glutamic acid Ca ions Ca current 神経細胞アミノ酸アミノ酸輸送 Ca電流

项目摘要

The purpose of this project was to investigate how chemical transmitters are released from retinal cells. Cells were isolated from the vertebrate retinae and voltage-clamped using a patch pipette in the whole-cell clamp configuration. The following results were obtained.1. The Ca current of mouse bipolar cells was of T type. The activation threshold was low and the current was not blocked by dihydropyridines. On the other hand, the Ca current of goldfish bipolar cells was of L type ; activation threshold was high, and the current was sensitive to dihydropyridines. In both species, Ca current was induced at the synaptic terminal as well as at the cell body. This observation suggests that the Ca current may play a key role in the transmitter release.2. Since glutamate is a leading candidate for the transmitter of bipolar cells, release of glutamate was examined by using bipolar cells isolated from the goldfish retina. Solitary catfish horizontal cells were used as a glutamate probe. It was demonstrated that gultamate (or closely related substance) was released from bipolar cells when the Ca current of synaptic terminal was activated by depolarization.3. Uptake mechanisms of transmitter were investigated electrophysiologically. Application of glutamate induced an inward current in salamander Muller cells (retinal glia). This current was due to the activation of electrogenic glutamate uptake carriers ; one molecule of glutamate was cotransported with three Na ions. The carrier showed a strong voltage-dependence and Ca ions were not required for its activation. Efflux of glutamate was observed but it was not electrogenic. This carrier seems to contribute to the Ca-independent release of transmitters.4. Turtle photoreceptors responded to glutamate with depolarization. Some response properties were similar to those of the glutamate carrier of salamander Muller cells. This suggests that turtle photoreceptors may have glutamate carriers.

这个项目的目的是研究化学递质是如何从视网膜细胞释放出来的。从脊椎动物视网膜中分离细胞，并使用膜片移液管在全细胞钳形中进行电压夹紧。得到了以下结果：小鼠双极细胞的Ca电流为T型。激活阈值低，电流不被二氢吡啶阻断。另一方面，金鱼双极细胞的Ca电流为L型；激活阈值高，电流对二氢吡啶敏感。在这两个物种中，Ca电流在突触末端和细胞体处都被诱导。这一观察结果表明，Ca电流可能在发射机释放中起关键作用。由于谷氨酸是双极细胞的主要候选递质，因此使用从金鱼视网膜分离的双极细胞来检测谷氨酸的释放。单独的鲶鱼水平细胞作为谷氨酸探针。结果表明，当突触末端的Ca电流被去极化激活时，双极细胞释放谷氨酸盐（或与其密切相关的物质）。从电生理角度探讨了递质摄取机制。谷氨酸的应用诱导了蝾螈Muller细胞（视网膜胶质细胞）的内向电流。这种电流是由于电致谷氨酸摄取载体的激活；一个谷氨酸分子与三个Na离子共运输。载体表现出很强的电压依赖性，其活化不需要钙离子。观察到谷氨酸的外排，但不是电致的。这种载波似乎有助于发射机的ca独立释放。海龟的光感受器对谷氨酸有去极化反应。部分响应特性与蝾螈Muller细胞谷氨酸载体相似。这表明海龟的光感受器可能有谷氨酸载体。