摘要
目的:研究小鼠球囊Ⅱ型前庭毛细胞乙酰胆碱(ACh)-敏感性钾电流的药理学特性以及钙离子对ACh-敏感性钾电流的调制作用。方法:应用全细胞膜片钳技术研究新鲜分离的小鼠球囊Ⅱ型前庭毛细胞ACh-敏感性钾电流的药理学特性以及细胞内外钙离子对ACh-敏感性钾电流的影响。结果:(1)细胞外ACh激活一缓慢持久的外向性电流。ACh-敏感性电流对钾通道阻断剂四乙胺(TEA,tetraethylammonium)和卡律布德蝎毒素(CTX,charybdotoxin)敏感,而对4-氨基吡啶(4-AP,4-aminopyride)不敏感。(2)细胞内应用钙离子螯合剂EGTA(ethylene glycol-bis(β-aminoethyl ether)-N,N,N,N-tetra-acetic acid),ACh-敏感性钾电流的幅值逐渐被抑制;细胞内预先应用肝素(heparin)阻断三磷酸肌醇-依赖性钙离子释放,ACh-敏感性钾电流的幅值不受影响。(3)ACh-敏感性钾电流对钙通道阻断剂Cd2+和Ni2+敏感。结论:细胞外ACh激活小鼠球囊Ⅱ型前庭毛细胞产生大电导钙依赖性钾电流(BK)。ACh-敏感性BK电流的活动依赖于细胞外钙离子通过膜上钙通道的内流,而三磷酸肌醇-依赖性细胞内钙离子释放机制不参与ACh-敏感性BK电流的激活过程。
AIM： To explore the properties of the acetylcholine （ACh） - sensitive potassium channel in type Ⅱ vestibular hair cells （ VHCs Ⅱ） in mice saccular macula and the modulation effect of calcium ions. METHODS ： Under the whole - cell patch mode, the pharmacology properties of ACh - sensitive potassium channel and the modulation of calcium ions on ACh -sensitive potassium channel were investigated. RESULTS： Following extracellular perfusion of ACh, VHCs Ⅱ displayed a slow and sustained outward current, which was sensitive to tetraethylammonium （TEA, 5 mmol/L） and charybdotoxin （ CTX, 100 nmol/L）, but not sensitive to 4 - aminopyride （4 - AP, 15μmol/L）. ACh - sensitive potassium current was inhibited by intracellular application of ethylene glycol - bis （ B - aminoethylether） - N, N, N＇, N＇ - tetraacetic-acid （EGTA, 5 mmol/L） and extracellular perfusion of Cd^2＋ and Ni^2＋ , respectively. Intracellular application of heparin （8 g/L） failed to inhibit ACh -sensitive potassium current. CONCLUSION： Extracellular application of ACh activates the big conductance, calcium-dependent potassium current （BK） in VHCs Ⅱ of mice, which is potently modulated by extracellular Ca^2＋ ions. However, intracellular IP3 -dependent Ca^2＋ ions release mechanism is not involved in the activation of the ACh - sensitive BK channel.
出处
《中国病理生理杂志》
CAS
CSCD
北大核心
2007年第10期1955-1958,共4页
Chinese Journal of Pathophysiology
基金
国家自然科学基金资助项目(No.30070809No.30371525No.30700934)
关键词
前庭
毛细胞
乙酰胆碱
钾通道
钙激活
Vestibule
Hair cells
Acetylcholine
Potassium channels, calcium - activated
