一氧化氮 (NO) 在天竺鼠耳蝸外毛細胞調節電壓依賴性鉀離子電流之研究

The study of the effect of Nitric Oxide on the Voltage-Dependant K＋Current of Outer Hair Cells in guinea pig cochlea

鄧雅方(Ya-Fang Teng)

指導教授 ： 林明忠 ； 林瑞生

中山醫學大學/醫學院/醫學研究所/碩士(2007年)

https://doi.org/10.6834/CSMU.2007.00037

摘要

本研究探討單離的天竺鼠耳蝸外毛細胞中一氧化氮 (NO) 及一氧化氮/環鳥糞嘌呤和鉀離子電流途徑 (nitric oxide/cyclic guanosine monophosphate ： NO/c-GMP pathway) 的關係。將聽覺反射靈敏的天竺鼠隨機分成七組，取出天竺鼠耳蝸中的外毛細胞利用細胞膜鉗定技術測量加入藥物前後的鉀離子電流之影響，分別加入 (1) Diaminopyridine (3,4-DAP)：非選擇性鉀離子通道阻斷劑 (2) L-arginine (L-Arg)：一氧化氮前趨物 (3) NG-nitro-L-arginine methyl ester hydrochloride ( L-NAME)：非選擇性 NOS 抑制劑 (4) Diethylamine NONOate (DEA-NO)：NO 供體 (5) S-nitroso-N- acetylpenicillamine (SNAP)： NO 供體 (6) dibutyryl cyclic guanosine 3':5' monophosphate (dbcGMP ) : cGMP 類似物和 (7) KT5823 : 抑制 c-GMP 依賴性蛋白激酶 PKG 於單離的天竺鼠耳蝸外毛細培養液中，探討上述一氧化氮及一氧化氮/環鳥糞嘌呤途徑相關藥劑對鉀離子電流之影響。
實驗結果顯示， L-Arg、SNAP、DEA-NO 均可引起單離外毛細胞的全細胞膜鉀離子電流增大。以 NOS 抑制劑 L-NAME 前處理可抑制L-Arg 增加鉀電流的作用。由此可見外毛細胞膜中 NO 的含量增加，可增加外毛細胞的鉀離子通道打開，而使鉀離子電流增大。因為 KT5823 和 db-cGMP 對單離外毛細胞的全細胞膜鉀離子電流之影響，和對照組相比較均顯示不具顯著差異，若再加入 L-Arg 發現測得外細胞細胞膜鉀離子電流有明顯增大之情形。從本研究結果我們認為外毛細胞鉀離子電流之調控，是經由細胞內 NO 含量增加，直接調節外毛細胞膜上鉀離子管道，使鉀離子電流增加，至於 cGMP-PKG 路徑，對外毛細胞膜上鉀離子電流並無直接的影響。

關鍵字

一氧化氮 ； 電壓依賴性鉀離子電流 ； 外毛細胞

並列摘要

The purpose of the present investigation is to study the effect of NO and NO/cGMP pathway on the potassium current of outer hair cells. This study utilized isolated guinea-pig outer hair cells and the whole cell patch-clamp technique to determine whether NO and NO/cGMP signaling pathway involved in modulating the K+ channels of outer hair cells.

The isolated outer hair cells were divided into seven groups as follows: group 1 treated with 3,4-diaminopyridine (3,4-DAP); group 2 with L-arginine (L-Arg); group 3 with NG-nitro-L-arginine methyl ester hydrochloride (L-NAME); group 4 with S-niroso-N-acetylpenicillamine (SNAP); group 5 with diethylamine NONOate(DEA-NO); group 6 with dibutyryl cyclic guanosine 3’:5’ monophosphate and group 7 with KT5823.

L-arginine, a nitric oxide precursor increased the amplitude of K+ current by 134.48% to the control at +60 mV holded. The NO donor S-niroso-N-acetylpenicillamine (SNAP) and diethylamine NONOate (DEA-NO) were also enhanced the current amplitude by 85.86 % and 103.37 % respectively. However, treated with PKG inhibitor (KT5823) and cGMP analogue (dbcGMP) did not significantly effect on the K+ current of outer hair cells.

These results suggest that NO acting directly on the channel protein and increasing the K+ current amplitude without cGMP-PKG signaling pathway involved.

並列關鍵字

Nitric Oxide；Voltage-Dependant K＋；Outer Hair Cells

參考文獻

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