What they found
Primary quantitative source for RWM permeability and scala tympani clearance. Used TMPA (trimethylphenylammonium — a low-MW ion) as marker in guinea pig. Applied to intact RWM for 90 min; measured distribution with ion-selective microelectrodes at turns 1 and 2.
After 90 min:
- Turn 1 (1.4 mm from base): 330 ± 147 μM (n=8)
- Turn 2 (7.5 mm from base): 15 ± 33 μM (n=5)
Simulation fitting yielded the canonical parameter set for the WUSTL Cochlear Fluids Simulator default (guinea pig).
Numbers that matter
| Parameter | Value | Units | Notes |
|---|---|---|---|
| RWM permeability (TMPA, low MW) | 1.9 × 10⁻⁸ | cm/s | Guinea pig; low-MW ion |
| ST clearance half-time | 60 | min | = 0.693/h → K_clear ≈ 0.69/h |
| Longitudinal perilymph flow | 4.4 | nL/min (base→apex) | Guinea pig |
Critical limitation: TMPA is a small ion (MW ~166 Da). The paper does NOT provide permeability for 14 kDa peptides. The model’s K_RWM = 0.02/h citing “Salt 2011” cannot be traced to this paper — and the 2001 value would be for a very different (small) molecule.
What this paper does NOT provide
- No MW scaling table for RWM permeability
- No human-specific parameters (all guinea pig)
- No middle ear clearance rate
- Guinea pig ST clearance t½ = 60 min ≠ human
Access status
PAYWALLED — ScienceDirect, Hearing Research Vol.154(1-2):88-97. Not on PMC. Needs institutional access or Sci-Hub.
Connections
[source]hydrogel_phase4e_cochlear_pkpd — K_PERILYMPH_CLEAR baseline (guinea pig 60 min t½); K_RWM is not from this paper- 2018-salt-plontke-pharmacokinetic-principles-inner-ear