IONIC BASIS OF THE RECEPTOR POTENTIAL IN A VERTEBRATE HAIR CELL
IONIC BASIS OF THE RECEPTOR POTENTIAL IN A VERTEBRATE HAIR CELL
复制标题
DOI：
10.1038/281675a0
复制
发表时间：
1979-01-01
期刊：
影响因子：
64.8
通讯作者：
HUDSPETH, AJ
中科院分区：
文献类型：
--
作者：
COREY, DP;HUDSPETH, AJ
脊椎动物的毛细胞是听觉、前庭和侧线器官的主要受体，发生在分离不同离子组成液体的上皮中。毛细胞的顶端表面，即机械敏感毛束所在的表面，面对着高k +的液体（内耳称为内淋巴）；基底外侧表面接触的是与其他细胞外液成分相似的液体（淋巴周围或相关物质）1 - 3。脊椎动物毛细胞顶端表面普遍存在高k +流体，这证明它对转导过程很重要，特别是它与受体电位下电导变化的离子特异性有关。然而，关于这种特异性的实验证据相互矛盾。K+通常被认为携带受体电流，因为豚鼠耳蜗内淋巴被淋巴周围取代，从而消除了细胞外记录的传声器电位6。然而，在其他制剂中，当毛细胞的顶表面面对高na +盐水时，以及当K+的电化学梯度接近0时，已经记录了麦克风电位以及细胞内受体电位。Ca2+也被认为携带受体电流8，但其浓度在内淋巴中相当低3，特别是在哺乳动物耳蜗中。我们在此提出证据表明，脊椎动物毛细胞中的受体电流是由体内的K+携带的，但转导通道实际上是非特异性的，可渗透到Li+， Na+, K+, Rb+, Cs+， Ca2+和至少一种小有机阳离子。
Vertebrate hair cells, the primary receptors of auditory, vestibular and lateral-line organs, occur in epithelia which separate fluids of differing ionic composition. The apical surfaces of hair cells, on which the mechanosensitive hair bundles are situated, face a high-K+fluid (termed endolymph in the inner ear); the basolateral surfaces instead contact fluid (perilymph or a related substance) of a composition similar to that of other extracellular fluids1–3. The universal occurrence of high-K+fluid on the apical surfaces of hair cells in vertebrates has been taken as evidence that it is important for the transduction process, in particular that it relates to the ionic specificity4of the conductance change5underlying the receptor potential. There is, however, conflicting experimental evidence regarding this specificity. K+has generally been thought to carry the receptor current, as replacement of endolymph with perilymph in the guinea pig cochlea abolishes the extracellularly recorded microphonic potential6. Yet microphonic potentials, as well as intracellular receptor potentials, have been recorded in other preparations when the apical surfaces of the hair cells faced instead a high-Na+saline, and thus when the electrochemical gradient for K+was near zero5,7. Ca2+has also been proposed to carry the receptor current8, but its concentration is quite low in endolymph3, particularly that of the mammalian cochlea9. We present evidence here that the receptor current in a vertebrate hair cell is carriedin vivoby K+, but that the transduction channel is in fact nonspecific, being permeable to Li+, Na+, K+, Rb+, Cs+, Ca2+, and at least one small organic cation.