对Hensen细胞在耳蜗K^+循环中角色的新认识

New Understanding of the Role of Hensen Cells in Cochlear Potassium Cycle

既往人们的研究重点主要在毛细胞和相关的神经通路,而对于毛细胞外侧的支持细胞的结构以及在内耳中的生理功能的研究不够深入,所以人们认为支持细胞仅仅起到支撑毛细胞以及稳定基底膜结构的作用,然而在最新研究中发现,支持细胞中尤其是Hensen细胞在内耳钾离子循环中扮演着重要的角色。在声音刺激时,毛细胞受到了机械刺激,钾离子通道开启,大量钾离子由内淋巴进入毛细胞,再被Hensen细胞、Deiters细胞等支持细胞所摄取,而上述支持细胞可产生外向性钾电流,将过多的钾离子通过缝隙连接或其他途径从支持细胞排出,依次转运至螺旋韧带,最终到达血管纹,再由血管纹泵入内淋巴,从而维持毛细胞微环境中钾离子循环及其平衡。耳蜗蜗内直流电位(endocochlear potential,EP)与中阶的高钾离子浓度密切相关,中阶的高钾主要来源于血管纹,在血管纹中多种细胞协同活动,以及耳蜗毛细胞、支持细胞等细胞有序的活动共同构成了钾离子循环,一旦钾离子循环受阻,可迅速导致EP下降,进而影响耳蜗电位,如微音器电位(cochlear microphonics potential,CM)。可见Hensen细胞对耳蜗功能的调节起着至关重要的作用。此外,耳蜗是一种具有免疫特性的器官,Hensen细胞上有Annexin蛋白(ANXA1)的表达。因此加强对Hensen细胞在耳蜗钾离子循环中的角色的新认识,可以对探讨耳蜗疾病的发生机制与发展提供新的思路。

Previous research has focused on hair cells and related neural pathways,with limited research on the structure and physiological functions of supporting cells lateral to hair cells,which were believed to only serve to support the hair cells and stabilize structures on the basilar membrane.It has been found in recent research that supporting cells,especially Hensen cells,play an important role in inner ear potassium cycle.When stimulated by sound,hair cells are mechanically excited,potassium channels are opened,a large amount of potassium ions enter hair cells from the endolymph and are taken up by support cells such as Hensen cells and Deiters cells,which can generate outward potassium currents.Excessive potassium ions are discharged from supporting cells through gap junctions or other channels,and are sequentially transported to the spiral ligament and finally the stria vascularis,which pumps potassium back into the endolymph to maintain potassium circulation and balance in the hair cell microenvironment.Endocochlear potential(EP)is closely related to high potassium concentration in the scala media,which is mainly maintained by the vascular striae,where a variety of cells cooperate with cochlear hair cells and support cells through orderly activities to form the potassium cycle.When the potassium cycle is blocked,EP quickly declines,affecting cochlear potentials,such as cochlear microphonics(CM).It can be seen that Hensen cells play a vital role in regulating cochlear function.In addition,the cochlea is an organ with immune properties,and Annexin protein(ANXA1)is expressed on Hensen cells.Therefore,new understanding of the role of Hensen cells in cochlear potassium cycle can provide new ideas for studying mechanisms and pathogenesis of cochlear diseases.