Potential changes of frog afferent terminals in response to dopamine.
Potential changes of frog afferent terminals in response to dopamine.
复制标题
青蛙传入末梢响应多巴胺的潜在变化。
DOI：
10.1016/0006-8993(85)91040-6
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发表时间：
1985
期刊：
影响因子：
2.9
通讯作者：
Davidoff,RA
中科院分区：
文献类型：
--
作者：
Ryan,GP;Hackman,JC;Wohlberg,CJ;Davidoff,RA
用蔗糖间隙技术研究了多巴胺对青蛙脊髓半横断后传入纤维膜电位的影响。在灌流的林格氏液中加入多巴胺后，最显著的效应是浓度低至0.01μM时的缓慢可逆超极化，其幅度和持续时间取决于浓度和作用时间。脊髓暴露于非选择性激动剂阿朴吗啡、D-1选择性激动剂SKF38393A或D-2选择性激动剂LY-14186，其超极化方式与多巴胺相似，但只有在较高浓度(100μM或更高)时才能引起背根超极化。阿朴吗啡也可引起迟发性去极化。非选择性多巴胺拮抗剂，氟奋乃静和氟哌啶醇，可逆地降低了多巴胺的作用。选择性D-2拮抗剂舒必利和甲氧氯普胺也有类似的作用，但对去甲肾上腺素引起的超极化无影响。多巴胺似乎不能激活肾上腺素能或5-羟色胺能受体，因为它的作用不受育亨宾、珊瑚碱、心得安或甲基丝氨酸的影响。多巴胺的作用似乎是由于它对传入纤维和中间神经元的作用。之所以得出这一结论，是因为通过向脐带灌流含有Mn2+离子、河豚毒素或甲苯蝶呤的溶液，多巴胺产生的潜在变化大大减少，但从未消除。多巴胺似乎有能力激活脊髓中的受体--这一作用会导致传入纤维的潜在变化。这些数据与多巴胺调节脊髓感觉传递的想法是一致的。
The actions of dopamine on the membrane potential of afferent fibers of the isolated hemisected frog spinal cord were studied by sucrose gap techniques. The most prominent effect seen after addition of dopamine to the superfusing Ringer's solution was a slow reversible hyperpolarization at concentrations as low as 0.01 μM; its amplitude and duration were dependent upon concentration and length of application. Biphasic responses with an initial dominant hyperpolarization and a much smaller, later depolarization were also noted and were particularly prominent when dopamine was applied at higher concentrations.Exposure of the cord to apomorphine, a non-selective agonist, to SKF 38393A, a D-1 selective agonist, or to LY-14186, a D-2 selctive agonist, hyperpolarized the dorsal root in a manner similar to that of dopamine, but only when the former compounds were applied at higher concentrations (100 μM or greater). Apomorphine also elicited a late depolarization. The non-selective dopamine antagonists, fluphenazine and haloperidol, reversibly reduced dopamine's actions. Similar effects were produced by the selective D-2 antagonists, sulpiride and metoclopramide, which had no effect on hyperpolarizations evoked by norepinephrine. Dopamine did not appear to activate adrenergic or serotonergic receptors, for its effects were not affected by yohimbine, corynanthine, propranolol, or methysergide. The effect of dopamine appeared to result from an action of the amine on both afferent fibers and interneurons. This inference was drawn because the potential changes produced by dopamine were substantially reduced, but never eliminated, by superfusion of the cord with solutions containing Mn2+ions, tetrodotoxin or mephenesin. Dopamine appears to have the ability to activate receptors in the spinal cord — an action which results in potential changes in afferents fibers. The data are compatible with the idea that dopamine modulates spinal sensory transmission.