POTASSIUM CURRENTS IN MAMMALIAN AND AVIAN ISOLATED TYPE-I SEMICIRCULAR CANAL HAIR-CELLS
POTASSIUM CURRENTS IN MAMMALIAN AND AVIAN ISOLATED TYPE-I SEMICIRCULAR CANAL HAIR-CELLS
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DOI：
10.1152/jn.1994.71.1.317
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发表时间：
1994-01-01
影响因子：
2.5
通讯作者：
CORREIA, MJ
中科院分区：
文献类型：
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作者：
RENNIE, KJ;CORREIA, MJ
1.从长爪沙鼠（Merionesunguiculatus）和白色王鸽（Columbalivia）半规管壶腹嵴分离出Ⅰ型前庭毛细胞。分离的I型细胞与II型毛细胞的区别在于它们的颈板比（NPR）和它们的特征性的双耳形。2.本文采用全细胞电压钳和电流钳技术，以黄曲霉素B为穿孔剂，研究了沙土鼠和鸽子Ⅰ型毛细胞的膜特性。3.在全细胞电流钳中，鸽子I型毛细胞的平均零电流电位V-z为-70 +/- 7（SD）mV（n = 18），沙鼠I型毛细胞的平均零电流电位V-z为-71 +/- 11 mV（n = 83）。4.在V-z，沙鼠和鸽子I型毛细胞，钾电流（I-KI）大于或等于50%激活。当膜电位超极化低于-90 mV时，该电流迅速失活。5. I-KI被外部施加的4-氨基吡啶（4-AP）（5 mM）和内部施加的20 mM四乙基铵（TEA）阻断。当4 mM钡存在于外部溶液中时，其也减少。钡的阻断程度随着膜电位的增加而增加。外部铯（5 mM）阻断了I-KI的内向成分。当I-KI被阻断时，V-z去极化约为40 mV。因此，I-KI似乎是一种延迟整流器，并且与不具有I-KI的分离的II型毛细胞相比，I-KI设置了分离的I型毛细胞所注意到的更负的V-z。6.第二个较小的钾电流出现在膜电位去极化高于-40 mV时。该电流可被30-50 mM外用TEA、100 μ M奎尼丁、100 nM蜂毒肽阻断，但不能被100 nM卡律巴毒素阻断，表明这是一种钙激活钾电流，I-K（Ca），不同于大多数其他毛细胞中发现的maxi-K钙激活钾电流。
1. Type I vestibular hair cells were isolated from the cristae ampullares of the semicircular canals of the Mongolian gerbil (Meriones unguiculatus) and the white king pigeon(Columba livia). Dissociated type I cells were distinguished from type II hair cells by their neck to plate ratio (NPR) and their characteristic amphora shape. 2. The membrane properties of gerbil and pigeon type I hair cells were studied in whole-cell voltage- and current-clamp using the perforated patch technique with amphotericin B as the perforating agent. 3. In whole-cell current-clamp, the average zero-current potential, V-z, measured for pigeon type I hair cells, was -70 +/- 7 (SD) mV (n = 18) and -71 +/- 11 mV (n = 83) for gerbil type I hair cells. 4. At V-z, for both gerbil and pigeon type I hair cells, a potassium current (I-KI) was greater than or equal to 50% activated. This current deactivated rapidly when the membrane potential was hyperpolarized below -90 mV. 5. I-KI was blocked by externally applied 4-aminopyridine (4-AP) (5 mM) and by internally applied 20 mM tetraethylammonium (TEA). It was also reduced when 4 mM barium was present in the external solution. The degree of block by barium increased as the membrane potential became more positive. External cesium (5 mM) blocked the inward component of I-KI. When I-KI was pharmacologically blocked, V-z depolarized by similar to 40 mV. Therefore I-KI appears to be a delayed rectifier and to set the more negative V-z noted for isolated type I hair cells when compared to isolated type II hair cells, which do not have I-KI. 6. A second, smaller potassium current was present at membrane potential depolarizations above -40 mV. This current was blocked by 30-50 mM, externally applied TEA, 100 mu M quinidine, 100 nM apamin, but not 100 nM charybdotoxin, indicating that this is a calcium-activated potassium current, I-K(Ca), different from the maxi-K calcium-activated potassium current found in most other hair cells.