Potentiation of transmitter release by protein kinase C in goldfish retinal bipolar cells
Potentiation of transmitter release by protein kinase C in goldfish retinal bipolar cells
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DOI：
10.1111/j.1469-7793.1998.219bf.x
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发表时间：
1998-10-01
影响因子：
5.5
通讯作者：
Tachibana, M
中科院分区：
文献类型：
--
作者：
Minami, N;Berglund, K;Tachibana, M
1.我们研究了是否可以通过激活视网膜双极细胞的蛋白激酶C（PKC）来改变递质的释放。从金鱼视网膜中分离出一个具有大轴突终末的双极细胞。采用全细胞电压钳技术测定突触前钙电流，并以鲶鱼水平细胞NMDA受体反应为指标，电生理检测突触前钙电流释放的递质（可能是谷氨酸）. PKC激活剂佛波醇12-肉豆蔻酸酯13-乙酸酯（PMA）可增强递质释放，但无效的佛波醇酯4 α-佛波醇12，13-二癸酸酯则不能增强递质释放。一个PKC抑制剂，双吲哚马来酰亚胺I，本身并不影响递质释放，但阻止PMA诱导的增强递质释放。这些结果表明PMA的作用是通过激活PKC介导的。将5 mM EGTA引入双极细胞的突触前末梢揭示了两个独立的递质释放组分。快速成分在去极化后立即触发，而慢成分则延迟出现。PMA的应用选择性地增强了慢成分，而不影响胞吐的Ca 2+依赖性.我们认为，PKC的激活可能会改变视网膜双极细胞突触囊泡的募集过程。
1. We examined whether transmitter release could be modified by the activation of protein kinase C (PKC) of retinal bipolar cells. A bipolar cell with a large axon terminal was isolated from the goldfish retina. The presynaptic Ca2+ current was measured under whole-cell voltage clamp, and the released transmitter (probably glutamate) was detected electrophysiologically by using the response of NMDA receptors of catfish horizontal cells as a reporter.2. Transmitter release was potentiated by a PKC activator, phorbol 12-myristate 13-acetate (PMA), but not by an ineffective phorbol ester, 4 alpha-phorbol 12,13-didecanoate. A PKC inhibitor, bisindolylmaleimide I, did not affect the transmitter release by itself but blocked the PMA-induced potentiation of transmitter release. These results suggest that the actions of PMA were mediated via the activation of PKC.3. Introduction of 5 mM EGTA into the presynaptic terminals of bipolar cells revealed two separate components of transmitter release. A rapid component was triggered immediately after depolarization while a slow component appeared with a delay. Application of PMA selectively potentiated the slow component without affecting the Ca2+ dependence of exocytosis.4. We suggest that the activation of PKC may modify the recruitment process of synaptic vesicles in retinal bipolar cells.