Cochlear effects of locally applied inhibitors

Area of Science:

• Ototolaryngology
• Neuroscience
• Physiology

Background:

• The inner ear's endocochlear potential (EP) is crucial for hearing.
• Systemic drug delivery to the inner ear is hindered by biological barriers.
• The round window offers a direct route for localized inner ear drug administration.

Purpose of the Study:

• To investigate the effects of sodium-potassium-ATPase inhibitors and chloride transport inhibitors on the chinchilla inner ear EP.
• To evaluate the efficacy of the round window as a delivery route for these agents.

Main Methods:

• Drugs were applied to the round window membrane of chinchilla inner ears.
• Endocochlear potential (EP) was recorded from the basal turn.
• Control (saline), ouabain, vanadate, sanguiarine, furosemide, piretanide, and DIDS were tested.

Main Results:

• Ouabain and vanadate administration resulted in significant changes to the EP.
• Loop diuretics furosemide and piretanide markedly decreased the EP.
• Sanguiarine and DIDS did not significantly alter the EP.
• Saline application served as a valid control, showing no effect on EP.

Conclusions:

• Local application via the round window is a viable method for inner ear drug delivery.
• Sodium-potassium-ATPase activity influences the EP.
• The role of active chloride transport in maintaining the normal EP is questionable, particularly concerning loop diuretics and DIDS effects.