AUTHOR=Sadreev Ildar I. , Burwood George W. S. , Flaherty Samuel M. , Kim Jongrae , Russell Ian J. , Abdullin Timur I. , Lukashkin Andrei N. TITLE=Drug Diffusion Along an Intact Mammalian Cochlea JOURNAL=Frontiers in Cellular Neuroscience VOLUME=13 YEAR=2019 URL=https://www.frontiersin.org/journals/cellular-neuroscience/articles/10.3389/fncel.2019.00161 DOI=10.3389/fncel.2019.00161 ISSN=1662-5102 ABSTRACT=
Intratympanic drug administration depends on the ability of drugs to pass through the round window membrane (RW) at the base of the cochlea and diffuse from this location to the apex. While the RW permeability for many different drugs can be promoted, passive diffusion along the narrowing spiral of the cochlea is limited. Earlier measurements of the distribution of marker ions, corticosteroids, and antibiotics demonstrated that the concentration of substances applied to the RW was two to three orders of magnitude higher in the base compared to the apex. The measurements, however, involved perforating the cochlear bony wall and, in some cases, sampling perilymph. These manipulations can change the flow rate of perilymph and lead to intake of perilymph through the cochlear aqueduct, thereby disguising concentration gradients of the delivered substances. In this study, the suppressive effect of salicylate on cochlear amplification via block of the outer hair cell (OHC) somatic motility was utilized to assess salicylate diffusion along an intact guinea pig cochlea