並列タイトル等哺乳類の蝸牛の非興奮性組織である血管条の電気化学的特性の音に対する感受性
一般注記Excitable cochlear hair cells convert the mechanical energy of sounds into the electrical signals necessary for neurotransmission. The key process is cellular depolarization via K+ entry from K+-enriched endolymph through hair cells' mechanosensitive channels. Positive 80mV potential in endolymph accelerates the K+ entry, thereby sensitizing hearing. This potential represents positive extracellular potential within the epithelial-like stria vascularis; the latter potential stems from K+ equilibrium potential (EK) across the strial membrane. Extra- and intracellular [K+] determining EK are likely maintained by continuous unidirectional circulation of K+ through a putative K+ transport pathway containing hair cells and stria. Whether and how the non-excitable tissue stria vascularis responds to acoustic stimuli remains unclear. Therefore, we analysed a cochlear portion for the best frequency, 1 kHz, by theoretical and experimental approaches. We have previously developed a computational model that integrates ion channels and transporters in the stria and hair cells into a circuit and described a circulation current composed of K+. Here, in this model, mimicking of hair cells' K+ flow induced by a 1 kHz sound modulated the circulation current and affected the strial ion transport mechanisms; the latter effect resulted in monotonically decreasing potential and increasing [K+] in the extracellular strial compartment. Similar results were obtained when the stria in acoustically stimulated animals was examined using microelectrodes detecting the potential and [K+]. Measured potential dynamics mirrored the EK change. Collectively, because stria vascularis is electrically coupled to hair cells by the circulation current in vivo too, the strial electrochemical properties respond to sounds.
The Journal of physiology. 2021, 599(19), 4497-4516.
新大院博(医)第1054号
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