大鼠和豚鼠外毛细胞胆碱能反应的差异。

Differences in cholinergic responses from outer hair cells of rat and guinea pig.

作者信息

Chen C, LeBlanc C, Bobbin R P

机构信息

Kresge Hearing Research Laboratory of the South, Department of Otorhinolaryngology and Biocommunication, Louisiana State University Medical Center, New Orleans 70112-2234, USA.

出版信息

Hear Res. 1996 Sep 1;98(1-2):9-17. doi: 10.1016/0378-5955(96)00049-4.

DOI:10.1016/0378-5955(96)00049-4

PMID:8880176

Abstract

A cholinergic receptor on outer hair cells (OHC) in guinea pig cochlea induces a K+ current when it is activated by acetylcholine and suberyldicholine but not by nicotine or muscarine (Bobbin, 1995). This unusual receptor may contain an alpha 9-subunit. However, the pharmacology of the alpha 9-subunit cloned from rat and expressed in Xenopus oocytes does not completely match that obtained for the ACh receptor in guinea pig OHCs. The response to 1,1-dimethyl-4-phenylpiperazinium (DMPP) is large in guinea pig OHCs and small in oocytes containing receptors of the alpha 9-subunit. Therefore, we compared the effects of cholinergic receptor agonists in rat and guinea pig OHCs using the whole-cell variant of the patch-clamp technique. ACh caused the largest outward K+ current in OHCs from both rat and guinea pig. Carbachol- and suberyldicholine-induced responses were similar in magnitude in OHCs of rat and guinea pig. However, DMPP produced a small response in OHCs from rat and a large response in OHCs from guinea pig. At a concentration of 100 microM, muscarine, oxotremorine M, nicotine and cytisine induced little response in guinea pig OHCs and none in rat OHCs. Results suggest that the ACh receptor on rat OHCs is similar to the alpha 9-subunit-containing receptor expressed in oocytes but different from the ACh receptor on guinea pig OHCs.

摘要

豚鼠耳蜗外毛细胞（OHC）上的一种胆碱能受体在被乙酰胆碱和辛二酰胆碱激活时会诱导钾离子电流，而被尼古丁或毒蕈碱激活时则不会（博宾，1995年）。这种不寻常的受体可能含有α9亚基。然而，从大鼠克隆并在非洲爪蟾卵母细胞中表达的α9亚基的药理学特性与豚鼠OHC中乙酰胆碱受体的药理学特性并不完全匹配。豚鼠OHC对1,1 - 二甲基 - 4 - 苯基哌嗪鎓（DMPP）的反应很大，而在含有α9亚基受体的卵母细胞中反应很小。因此，我们使用膜片钳技术的全细胞变体比较了胆碱能受体激动剂对大鼠和豚鼠OHC的影响。乙酰胆碱在大鼠和豚鼠的OHC中都引起了最大的外向钾离子电流。卡巴胆碱和辛二酰胆碱诱导的反应在大鼠和豚鼠的OHC中幅度相似。然而，DMPP在大鼠OHC中产生的反应较小，而在豚鼠OHC中产生的反应较大。在100微摩尔浓度下，毒蕈碱、氧化震颤素M、尼古丁和金雀花碱在豚鼠OHC中诱导的反应很小，在大鼠OHC中则无反应。结果表明，大鼠OHC上的乙酰胆碱受体与在卵母细胞中表达的含α9亚基的受体相似，但与豚鼠OHC上的乙酰胆碱受体不同。