Abstract
Endolymph, the extracellular solution in the cochlea of the inner ear, exhibits a unique potential of +80 mV called endocochlear potential (EP). We previously identified by electrophysiological experiments that the EP depends on two K+-diffusion potentials in the two epithelial layers in the stria vascularis that comprises inner and outer epithelial layers, and also showed by theoretical approach that the electrochemical environment in the cochlea including the endolymph is maintained by the K+-circulation throughout this organ. Ion-transport mechanism in the basolateral surface of the outer layer, which consisted primarily of fibrocytes of spiral ligament, remains unknown. Na+, K+-ATPase and Na+, K+, 2Cl- cotransporter (NKCC) that occur together in this membrane domain and have been believed to be involved in the K+-circulation. However, our recent study strongly suggests that the Na+, K+-ATPase functionally dominates but NKCC's contribution is limited. Based on the experimental data, we will develop a new mathematical model to reconstitute the EP and K+-circulation in silico and account for the relationship between the two.
