Co-location of Ach-sensitive BK channels and L-type calcium channels in type Ⅱ vestibular hair cells of guinea pig
10.3321/j.issn:1673-0860.2008.03.011
- VernacularTitle:豚鼠Ⅱ型前庭毛细胞乙酰胆碱敏感性大电导钙依赖性钾通道与L型钙通道共存
- Author:
Chang-Kai GUO
1
;
Guan-Qiao LI
;
Wei-Jia KONG
;
Song ZHANG
;
Ting-Ting WU
;
Jia-Li LI
;
Qing-Tian LI
Author Information
1. 华中科技大学同济医学院附属协和医院
- Keywords:
Hair cells,vestibular;
Large-conductance calcium-activated potassium channels;
Calcium channels,L-type;
Patch-clamp techniques
- From:
Chinese Journal of Otorhinolaryngology Head and Neck Surgery
2008;43(3):208-212
- CountryChina
- Language:Chinese
-
Abstract:
Objective To explore the mechanisms of the influx of calcium ions during the activation of Ach-sensitive BK channel(big conductance,calcium-dependent potassium channel)in type Ⅱ vestibular hair cells of guinea pigs. Methods Type Ⅱ vestibular hair cells were isolated by collagenase type IA.Under the whole-cell patch mode,the sensitivity of Ach-sensitive BK current to the calcium channels blockers was investigated,the pharmacological property of L-type calcium channel activator-sensitive current and Ach-sensitive BK current was compared. Results Following application of Ach, type Ⅱ vestibular hair cells displayed a sustained outward potassium current,with a reversal potential of(-70.5±10.6)mV(-x±s,n=10). At the holding potential of -50 mV, the current amplitude of Ach-sensitive potassium current activated by 100 μmol/L Ach was(267±106) pA(n=11). Ach-sensitive potassium current was potently sensitive to the BK current blocker, IBTX(iberiotoxin, 200 nmol/L). Apamin,the well-known small conductance, calcium-dependent potassium current blocker, failed to inhibit the amplitude of Ach-sensitive potassium current at a dose of 1 μmol/L. Ach-sensitive BK current was sensitive to NiCl2 and potently inhibited by CdCl2. NiCl2 and CdCl2 showed a dose-dependent blocking effect with a half inhibitionmaximal response of(135.5±18.5)μmol/L(n=7) and (23.4±2.6) μmol/L(n=7). The L-type calcium channel activator,(-)-Bay-K 8644(10 μmol/L),mimicked the role of Ach and activated the IBTX-sensitive outward current. Conclusion Ach-sensitive BK and L-type calcium channels are co-located in type Ⅱ vestibular hair cells of guinea pigs.
