Cochlear Fluids Simulator - Example Output

Round Window Application in the Guinea Pig

1) Simulation of entry of solute with diffusion coefficient 0.65 x 10-5 cm2/s, equivalent to gentamycin, as a result of delivery to the round window membrane. 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 far higher drug concentrations are achieved in the basal turn than in the apical turn.

 

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

 

3) Calculation identical to Figure 1, except the revised version of the simulator (V 1.1) was used in which the round window membrane applies solute to a region of the base, rather than the single, basal-most element. In this simulation, the RW has been assumed to extend apically 0.5 mm from the base, (AN ARBITRARY VALUE UNTIL WE MEASURE THIS) as shown in the figure. Note that the spread of solute along scala tympani is little affected in the guinea pig (Compare this Figure with Figure 1), because the scala is wide at the base. The same is not true for other species, such as the gerbil and the mouse.

 

4) Concentration versus distance plot for round window delivery in the revised (1.1) version of the model as shown in Figure 3. Although more solute enters the cochlea (compare with Figure 2), spread of solute is limited primarily by diffusion.