[Experimental studies on the effect of labyrinth anesthesia]

Area of Science:

• Oto-neuroscience and pharmacology
• Inner ear physiology and drug effects

Context:

• The stria vascularis plays a crucial role in maintaining the electrochemical gradient of the endolymph.
• Understanding the effects of local anesthetics like tetracaine on inner ear function is vital for otologic procedures.

Purpose:

• To investigate the direct effects of tetracaine on the electrogenic pump of stria vascularis cells.
• To determine tetracaine's impact on endolymphatic DC potential, ion activity, membrane permeability, and oxygen levels.

Summary:

• Tetracaine injection into the tympanic cavity inhibits the stria vascularis electrogenic pump, independent of round window membrane damage.
• Tetracaine reduces endolymphatic DC potential dose-dependently, without affecting K+-Cl- activity or Reissner's membrane permeability.
• A significant increase in endolymph oxygen pressure near the stria vascularis was observed following 4% tetracaine administration.

Impact:

• Provides insights into the mechanism by which tetracaine affects inner ear bioelectrical properties.
• Suggests potential implications for managing inner ear fluid homeostasis and oxygenation during otologic interventions.