Investigation on the transmitter substance released from vertebrate photoreceptors.

脊椎动物光感受器释放的递质物质的研究。

基本信息

批准号：
63570066
负责人：
KAWAMURA Satoru
金额：
$ 1.34万
依托单位：
Keio University School of Medicine
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1988
资助国家：
日本
起止时间：
1988 至 1989
项目状态：
已结题

项目摘要

Though the transmitter of a vertebrate photoreceptor has not been known yet, circumstantial evidence suggests that aspartate or glutanate could be the transmitter. The purpose of this study is to identify the transmitter substance released from rod photoreceptors.Rod photoreceptors were isolated with mechanical dissociation of carp retinas. Twenty to eighty percent of the isolated rods retained their axons and 25 - 50 % of then had axon terminals. These cells were perfused with solutions of known chemical and ionic composition. Amino acids which were released from the rods into the perfusion solution were analyzed with high performance liquid chromatography. Though we expected the release of aspartate or glutagate in the dark, we observed the release of almost all of the amino acids. Moreover, the release of these amino acids was not affected by a light stimulation. On the other hand, when the cells were depolarized with a treatment of a high-K^+ solution or a low Ca^<2+>-solution, the release was facilitated. Again, it was none-specific. This "depolarization-induced release" did not require the presence of Ca^<2+> since in the presence of Co^<2+> and in the absence of Ca^<2+>, we still observed the increase in the amino acid release. Though the isolated rod retained axon or axon terminal, we were not sure whether these cells released these amino acids from the cite which is actually involved in the transmitter release in intact cells. It may be true that the population of the intact cells which could release the transmitter in a light-dependent manner was too low in our preparation. However, the present work did indicate that the conventional criteria --release of the substance upon depolarization-- is not sufficient to identify the transmitter and that careful study is needed to solve this issue.

尽管尚不知道脊椎动物感光器的发射器，但间接证据表明天冬氨酸或谷氨酸可能是发射机。这项研究的目的是鉴定从杆感光体释放的发射器物质。用鲤鱼视网膜的机械解离，将rod光感受器分离出来。 20％至80％的孤立杆保留了轴突，当时有25-50％的轴突末端。这些细胞用已知的化学和离子成分溶液灌注。用高性能液相色谱分析了从棒中释放到灌注溶液中的氨基酸。尽管我们期望天冬氨酸在黑暗中释放或谷助释放，但我们观察到了几乎所有氨基酸的释放。此外，这些氨基酸的释放不受光刺激的影响。另一方面，当细胞用高k^+溶液或低Ca^<2+> - 溶液的处理将细胞去极化时，促进释放。同样，这不是特定的。这种“去极化诱导的释放”不需要Ca^<2+>的存在，因为在存在Co^<2+>的情况下，并且在不存在Ca^<2+>的情况下，我们仍然观察到氨基酸释放的增加。尽管分离的杆保留了轴突或轴突末端，但我们不确定这些细胞是否从列举中释放了这些氨基酸，这实际上涉及完整细胞中的发射机释放。可能确实以光依赖性方式释放发射机的完整细胞的种群在我们的制备中太低。但是，目前的工作确实表明，传统标准 - 去极化时物质的释放 - 不足以识别发射机，需要仔细的研究来解决此问题。