Evidence for an Na(+)-K(+)-Cl- cotransporter in mammalian type I vestibular hair cells.
Evidence for an Na(+)-K(+)-Cl- cotransporter in mammalian type I vestibular hair cells.
复制标题
哺乳动物 I 型前庭毛细胞中存在 Na( )-K( )-Cl- 协同转运蛋白的证据。
DOI：
10.1152/ajpcell.1997.273.6.c1972
复制
发表时间：
1997
期刊：
影响因子：
--
通讯作者：
Correia,MJ
中科院分区：
文献类型：
--
作者：
Rennie,KJ;Ashmore,JF;Correia,MJ
In amniotes, there are two types of hair cells, designated I and II, that differ in their morphology, innervation pattern, and ionic membrane properties. Type I cells are unique among hair cells in that their basolateral surfaces are almost completely enclosed by an afferent calyceal nerve terminal. Recently, several lines of evidence have ascribed a motile function to type I hair cells. To investigate this, elevated external K+, which had been used previously to induce hair cell shortening, was used to induce shape changes in dissociated mammalian type I vestibular hair cells. Morphologically identified type I cells shortened and widened when the external K+concentration was raised isotonically from 2 to 125 mM. The shortening did not require external Ca2+but was abolished when external Cl−was replaced with gluconate or sulfate and when external Na+was replaced withN-methyl-d-glucamine. Bumetanide (10–100 μM), a specific blocker of the Na+-K+-Cl−cotransporter, significantly reduced K+-induced shortening. Hyposmotic solution resulted in type I cell shape changes similar to those seen with high K+, i.e., shortening and widening. Type I cells became more spherical in hyposmotic solution, presumably as a result of a volume increase due to water influx. In hypertonic solution, cells became narrower and increased in length. These results suggest that shape changes in type I hair cells induced by high K+are due, at least in part, to ion and solute entry via an Na+-K+-Cl−cotransporter, which results in cell swelling. A scheme is proposed whereby the type I hair cell depolarizes and K+leaves the cell via voltage-dependent K+channels and accumulates in the synaptic space between the type I hair cell and calyx. Excess K+could then be removed from the intercellular space by uptake via the cotransporter.
