Chesnoy-Marchais D
Brain Res. 1984 Jun 18;304(1):83-91. doi: 10.1016/0006-8993(84)90863-1.
The inhibitory response to dopamine (DA) of the Aplysia burster R15 has been attributed previously either to a K+ conductance increase or to a decrease of the slow inward current (SIC) which is responsible for the bursting activity of R15. The present study reexamines the main points which are at the origin of this controversy. It is shown that the response to short applications of DA is actually sensitive to the extracellular K+ concentration and that this response may always be inverted by hyperpolarization of the cell below EK (at least in a high-K+ solution). The results suggest that short applications of DA induce an increase in K+ conductance rather than a blockade of the SIC. This conclusion is strengthened by the effects of intracellular Cs+ injections and by Ca2+-removal experiments. Prolonged DA perfusions may occasionally induce a second slow response in addition to the initial K+ conductance increase. This slow component of the DA response, which may imply modifications of the synaptic activity, does not seem to result either from a K+ conductance increase or from a blockade of the SIC.
此前，海兔爆发性神经元R15对多巴胺（DA）的抑制反应，要么归因于钾离子电导增加，要么归因于负责R15爆发活动的缓慢内向电流（SIC）减少。本研究重新审视了这一争议产生的要点。结果表明，对短时间施加DA的反应实际上对细胞外钾离子浓度敏感，并且这种反应总是可以通过将细胞超极化至低于EK（至少在高钾溶液中）而反转。结果表明，短时间施加DA会导致钾离子电导增加，而不是阻断SIC。细胞内注射铯离子的效果以及去除钙离子的实验强化了这一结论。长时间灌注DA除了最初的钾离子电导增加外，偶尔还可能诱导第二种缓慢反应。DA反应的这种缓慢成分可能意味着突触活动的改变，似乎既不是由钾离子电导增加引起的，也不是由SIC阻断引起的。
