Round Window Application in the Mouse

1) Simulation of gentamycin entry (diffusion coefficient 0.65 x 10-5 cm2/s) by delivery to the round window membrane using the original version (V 1.0) of the simulator.. The calculation assumes the presence of cross-communication between scala tympani and scala vestibuli across the spiral ligament, and clearance from the perilymphatic scala with a half time of 120 mins. Note that some drug reaches the apical turn within 60 mins, as the mouse cochlea is small.

2) Display of solute concentration versus distance for the same conditions as shown in Figure 1.calculated with Version 1.0 of the simulator The concentration applied to the RW is assumed to be constant at 1000 (arbitrary concentration units, e.g.. 1000 uM).

3) RW entry for the same conditions as Figure 1, but with the RW membrane extending 0.5 mm from the base as now permitted by V 1.1 of the simulator. (NOTE: THIS FIGURE IS ARBITRARY AND IS CURRENTLY BEING MEASURED) The calculated results are considerably different from Figure 1, showing that for the mouse the geometry of the RW is an important issue which must be quantified.

4) Concentration versus distance plot with the revised model (V 1.1) which allows for the basal turn goemetry of the round window. Note that higher concentrations are achieved (compared with Figure 2) showing that correct simulation of the RW geometry is more important in this species than it is in other species, such as the guinea pig..