Fig. 4

In silico reproduction of electrochemical dynamics in the cochlea. A An outline of the original Nin–Hibino–Kurachi (NHK) model [29]. This model is characterized by outer and inner layers in the lateral wall and the hair cell layer, respectively. The profile of each of the six surfaces is represented by electrical circuits that contain ion channels and transporters. These circuits are connected in series and drive the K⁺ circulation current under normal conditions (see Fig. 3a). ClC ClC-K/barttin-type Cl⁻ channel, Cl⁻-T Cl⁻-transporter, MET mechanoelectrical transduction, Na⁺-T Na⁺-transporter. Reproduced and adapted from Nin et al. [24]. B Ionic dynamics in the lateral wall. Ba and Bb indicate major ionic flows underlying the maintenance of or change in the electrochemical properties of the cochlea under normal and anoxic conditions. See the main text for details. Reproduced and adapted from Nin et al. [24]. C The updated NHK model. In the recent model (right panel), a few ion transport molecules incorporated into the basolateral surface of the outer layer were changed on the basis of the experimental observations, as described in the main text and in references [33, 35]. Left panel indicates the corresponding portion in the original model. Reproduced and adapted from Yoshida et al. [36]. D Comparison of the experimental and simulated results. Da A microelectrode sensitive to the potential (red) and [K⁺] (blue) was inserted from PL into endolymph (EL) in a live guinea pig. After the passage, while the electrode was held in the IS, control artificial perilymph or a solution containing ouabain (10 µM), a blocker of Na⁺, K⁺-ATPases, was perfused into the perilymphatic space. The [K⁺] measurement highlighted by the dashed box is expanded in the inset. A wedge above the trace shows the period when the electrode was moved forward or backward. Db Illustration of a simulation of the experimental conditions shown in a via the recently updated NHK model. [K⁺] behavior indicated by the dashed box is enlarged in the inset. Reproduced and adapted from Yoshida et al. [35]