Ionic basis of presynaptic inhibitory potentials at crayfish claw opener.
Ionic basis of presynaptic inhibitory potentials at crayfish claw opener.
复制标题
小龙虾开爪器突触前抑制电位的离子基础。
DOI：
10.1152/jn.1980.43.6.1547
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发表时间：
1980
影响因子：
2.5
通讯作者：
P. A. Getting
中科院分区：
文献类型：
--
作者：
P. Fuchs;P. A. Getting
1. 克氏原螯虾（Procambarus clarkii）的开爪兴奋轴突的细胞内记录位于开爪肌表面轴突末端树枝附近。在20个细胞中，兴奋轴突的静息电位平均为- 80mv。动作电位振幅和持续时间平均分别为100 mV和2 ms。2. 开启抑制轴突的单个动作电位在兴奋轴突中产生超极化突触电位（平均振幅0.3 mV）。这种抑制性突触电位的明显逆转电位比在对照盐水中休息时负约5mv。未观察到兴奋轴突在静止状态下具有去极化突触电位。3. 当外部氯离子浓度从240 mM降低到24 mM时，表观反转电位平均去极化12 mV，而静止电位没有变化。在低氯盐溶液中，刺激抑制剂轴突引起的突触电位发生去极化。4. 外部钾离子浓度从5 mM增加到10 mM，使表观反转电位退极化16 mV；然而，静止电位去极化10mv。低的外部钾有相反的作用，引起休息电位和表观逆转电位的超极化。5. 突触前抑制在原螯鱼开爪神经肌肉连接似乎是由一个超极化突触电位介导。这些实验结果表明，氯离子充当突触前电位的电荷。钾作为载流子直接参与的证据是模棱两可的，因为涉及Cl的Donnan平衡效应。
1. Intracellular recordings from the claw opener excitor axon of the crayfish, Procambarus clarkii, were obtained near the terminal arborizations of the axon on the surface of the opener muscle. Rest potential in the excitor axon averaged --80 mV over 20 cells. Action-potential amplitude and duration averaged 100 mV and 2 ms, respectively. 2. A single action potential in the opener inhibitor axon produces a hyperpolarizing synaptic potential (average amplitude 0.3 mV) in the excitor axon. The apparent reversal potential of this inhibitory synaptic potential is approximately 5 mV more negative than rest in control saline. No excitor axons were observed to have depolarizing synaptic potentials at rest. 3. A decrease in external chloride concentration from 240 to 24 mM causes the apparent reversal potential to depolarize an average of 12 mV, with no change in rest potential. In low-chloride saline, the synaptic potential evoked by stimulation of the inhibitor axon becomes depolarizing. 4. An increase in external potassium concentration from 5 to 10 mM causes the apparent reversal potential to depolarize by 16 mV; however, rest potential depolarizes by 10 mV. Low external potassium has the opposite effects, causing both rest potential and the apparent reversal potential to hyperpolarize. 5. Presynaptic inhibition at the Procambarus claw opener neuromuscular junction appears to be mediated by a hyperpolarizing synaptic potential. The results of these experiments suggest that chloride serves as the charge for the presynaptic potential. The evidence for a direct involvement of potassium as a charge carrier is equivocal due to Donnan equilibrium effects involving Cl.