Goshima Y, Kubo T, Misu Y
Department of Pharmacology, Yokohama City University School of Medicine, Japan.
J Neurochem. 1988 Jun;50(6):1725-30. doi: 10.1111/j.1471-4159.1988.tb02470.x.
Biphasic electrical field stimulation (0.5-5 Hz, 2 ms, 25 V, 3 min) and high K+ (10-30 mM, 5 min) released endogenous 3,4-dihydroxyphenylalanine (DOPA) from superfused rat striatal slices. Characteristics of the DOPA release were compared with those of 3,4-dihydroxyphenylethylamine (dopamine, DA). Electrical stimulation at 2 Hz evoked DOPA and DA over similar time courses. alpha-Methyl-p-tyrosine (0.2 mM) markedly reduced release of DOPA but not of DA. Maximal release (0.3 pmol) of DOPA was obtained at 2 Hz and at 15 mM K+. The impulse-evoked release of DOPA and DA was completely tetrodotoxin (0.3 microM) sensitive and Ca2+ dependent and the 15 mM K+-evoked release was also Ca2+ dependent. On L-[3,5-3H]tyrosine (1 microM) superfusion, high K+ (15 and 60 mM) released DOPA and DA together with concentration-dependent decreases in tyrosine 3-monooxygenase (EC 1.14.16.2) activity as indicated by [3H]H2O formation, followed by concentration-dependent increases after DOPA and DA release ended. These findings suggest that striatal DOPA is released by a Ca2+-dependent excitation-secretion coupling process similar to that involved in transmitter release.
双相电场刺激（0.5 - 5赫兹，2毫秒，25伏，3分钟）和高钾（10 - 30毫摩尔，5分钟）可使灌流的大鼠纹状体切片释放内源性3,4 - 二羟基苯丙氨酸（多巴）。将多巴释放的特征与3,4 - 二羟基苯乙胺（多巴胺，DA）的特征进行了比较。2赫兹的电刺激在相似的时间进程中诱发了多巴和多巴胺的释放。α - 甲基 - 对 - 酪氨酸（0.2毫摩尔）显著降低了多巴的释放，但对多巴胺的释放没有影响。在2赫兹和15毫摩尔钾离子条件下获得了多巴的最大释放量（0.3皮摩尔）。冲动诱发的多巴和多巴胺释放完全对河豚毒素（0.3微摩尔）敏感且依赖钙离子，15毫摩尔钾离子诱发的释放也依赖钙离子。在L - [3,5 - ³H]酪氨酸（1微摩尔）灌流时，高钾（15和60毫摩尔）释放多巴和多巴胺，同时酪氨酸3 - 单加氧酶（EC 1.14.16.2）活性随浓度依赖性降低，这通过[³H]H₂O的形成得以体现，随后在多巴和多巴胺释放结束后随浓度依赖性增加。这些发现表明，纹状体多巴是通过一种与递质释放所涉及的过程类似的钙离子依赖性兴奋 - 分泌偶联过程释放的。
