Rapid correction of vestibular imbalance by intracochlear administration of ATP in a guinea pig model of unilateral peripheral vestibular disorder

Abstract

The effect of inner ear administration of adenosine triphosphate (ATP) on vestibular function was investigated in guinea pigs with vestibular disorder. The right lateral semicircular canal was cut surgically. Animals were then treated with saline, 5 mM ATP, 50 mM ATP, or 50 mM ATP+10 mM pyridoxal-phosphate-6-azophenyl-2′, 4′-disulfonic acid (PPADS), a P2X receptor antagonist, administered directly into the scala tympani by osmotic pump. Before treatment, and at 3, 5 and 7 days after treatment, trapezoid rotation tests were performed on all animals, and the post-rotatory nystagmus (PRN) ratio (number of nystagmus beats after counterclockwise rotation/number of nystagmus beats after clockwise rotation) was calculated and compared between groups. The PRN ratio was statistically greater at 5 days after treatment in the 50 mM ATP group than in the saline group. A statistical difference was also observed in animals treated with 50 mM ATP+10 mM PPADS. Our results indicate that ATP plays an important role in the vestibular periphery to correct vestibular imbalance and that this action may not occur via P2X receptors.