Kim Chang-Hee, Kim Hye-Young, Lee Ho Sun, Choi Byung Yoon, Chang Sun O, Oh Seung-Ha, Lee Jun Ho
Department of Otorhinolaryngology-Head and Neck Surgery, Konkuk University School of Medicine, Republic of Korea.
Auris Nasus Larynx. 2013 Jun;40(3):266-72. doi: 10.1016/j.anl.2012.06.008. Epub 2012 Oct 9.
The purpose of the present study was to investigate the effect of dopamine as a possible regulator of epithelial Na(+) channel (ENaC) in the Reissner's membrane (RM).
RM was freshly dissected from the gerbil cochlea, and short-circuit current (Isc) was measured using the voltage-sensitive vibrating probe technique. The dopamine receptor expression was examined using immunohistochemistry.
The results showed that dopamine induced activation of the amiloride-sensitive Isc, but not after pre-treatment with amiloride. The D1-like receptor antagonist SCH-23390, but not the D2-like receptor antagonist sulpiride, decreased the stimulatory effect of dopamine on RM. The effect of dopamine on Na(+) transport via ENaC was still observed after blockade of the Na(+)-K(+)-ATPase by ouabain. D1 receptor immunoreactivity was observed in RM, stria vascularis and spiral ganglion.
Na(+) transport in RM is activated by dopamine possibly via D1-like receptors, and intracellular mechanisms other than cAMP-mediated pathway may be involved.
本研究旨在探讨多巴胺作为内淋巴囊上皮钠通道（ENaC）潜在调节因子的作用。
从沙鼠耳蜗新鲜分离出内淋巴囊，采用电压敏感振动探针技术测量短路电流（Isc）。通过免疫组织化学检测多巴胺受体表达。
结果显示，多巴胺可诱导amiloride敏感的Isc激活，但在amiloride预处理后则无此现象。D1样受体拮抗剂SCH-23390可降低多巴胺对内淋巴囊的刺激作用，而D2样受体拮抗剂舒必利则无此作用。在用哇巴因阻断Na(+)-K(+)-ATP酶后，仍可观察到多巴胺对通过ENaC的Na(+)转运的作用。在内淋巴囊、血管纹和螺旋神经节中观察到D1受体免疫反应性。
多巴胺可能通过D1样受体激活内淋巴囊中Na(+)的转运，且可能涉及除cAMP介导途径以外的细胞内机制。
