The actions of the kappa 1 opioid agonist U-50,488 on presynaptic nerve terminals of the chick ciliary ganglion.
The actions of the kappa 1 opioid agonist U-50,488 on presynaptic nerve terminals of the chick ciliary ganglion.
复制标题
kappa 1 阿片类激动剂 U-50,488 对小鸡睫状神经节突触前神经末梢的作用。
DOI：
10.1016/0306-4522(93)90302-v
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发表时间：
1993
期刊：
影响因子：
3.3
通讯作者：
Chiappinelli,VA
中科院分区：
文献类型：
--
作者：
Fletcher,GH;Chiappinelli,VA
The actions of theκ1opioid receptor agonist U-50,488 (trans-(±)-3,4-dichloro-N-methyl-N-[2-(1-pyrrolidinyl) cyclohexyr]-benzene-acetamide methane sulfonate) on the membrane properties of presynaptic calyciform nerve terminals of the chick ciliary ganglion were examined using intracellular recordings obtained from intact ganglion preparations maintainedin vitro. U-50,488 produced a concentrationdependent (30–1000 μM) hyperpolarization with an apparent increase in input resistance. This hyperpolarization resulted from inhibition of the Na+-K+inward rectifier, since it was blocked by 3 mM Cs+and was not observed when terminals were depolarized beyond resting potential where inward rectification was voltage inactivated. A depolarizing effect on membrane potential with a further rise in input resistance was commonly observed at the highest perfused U-50,488 concentration (1 mM). The depolarizing event appears to result from a decrease in membrane potassium conductance, as the reversal potential for the response was estimated to be between −70 and −90 mV and the potassium channel blocker Ba2+(1mM) abolished the response. The κ1opioid receptor agonist also blocked spontaneously occurring miniature hyperpolarizations in the terminals, which are considered to be due to a Ca2+-dependent K+conductance. Most of the responses to U-50,488 were abolished in the presence of the κ1receptor antagonist norbinaltorphimine.In conclusion, the excitability of presynaptic nerve terminals in the chick ciliary ganglion can be modulated by the inhibition of at least three separate ion conductances following activation ofκ1opioid receptor sites in the nerve terminal region.
