ATP antagonists cibacron blue, basilen blue and suramin alter sound-evoked responses of the cochlea and auditory nerve

• Published in: Hearing research Vol. 78; no. 2; pp. 181 - 188
• Main Authors: Kujawa, S.G., Fallon, M., Bobbin, R.P.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.08.1994; Elsevier
• Subjects: Action Potentials - drug effects; Action Potentials - physiology; Adenosine Triphosphate - antagonists & inhibitors; Animals; ATP antagonists; Biological and medical sciences; Cochlea; Cochlea - drug effects; Cochlea - physiology; Coloring Agents; Dose-Response Relationship, Drug; Ear and associated structures. Auditory pathways and centers. Hearing. Vocal organ. Phonation. Sound production. Echolocation; Electrophysiology; Evoked Potentials, Auditory - drug effects; Evoked Potentials, Auditory - physiology; Female; Fundamental and applied biological sciences. Psychology; Guinea Pigs; Male; Otoacoustic Emissions, Spontaneous - drug effects; Protein Synthesis Inhibitors - pharmacology; Purinergic P2 Receptor Antagonists; Purinoceptors; Stereoisomerism; Suramin - pharmacology; Triazines - pharmacology; Vertebrates: nervous system and sense organs; Vestibulocochlear Nerve - drug effects; Vestibulocochlear Nerve - physiology; Cochlea; ATP antagonists; Purinoceptors; Otoacoustic emission; Cochlear potential; Rodentia; Electrophysiology; P2 Purinergic receptor; Action potential; Auditory nerve; Inner ear; Organ of hearing; Vertebrata; Mammalia; Guinea pig; Acoustic stimulus; Purinergic transmission; Auditory pathway
• ISSN: 0378-5955; 1878-5891
• DOI: 10.1016/0378-5955(94)90024-8

The P 2-purinergic receptor antagonists suramin, cibacron blue and basilen blue, the latter two being isomers of reactive blue 2, were studied for their effects on sound-evoked responses from the cochlea (cochlear microphonic, CM; summating potential, SP; distortion product otoacoustic emissions, DPOAE) and auditory nerve (compound action potential, CAP). Local application of these compounds (10–1000 αM) into the cochlear perilymph was associated with concentration-dependent response alterations. Effects of suramin on cochlear responses were minimal: High-intensity SP was reduced slightly at concentrations >- 330 αM without significant alterations in CM or DPOAEs. The amplitude of the auditory nerve CAP was suppressed and its latency increased at drug concentrations >- 100 αM. Cibacron blue and basilen blue were of greater potency in their effects on cochlear and auditory nerve responses. DPOAEs were generally reduced, low-intensity SP was reduced and high-intensity SP was increased and CM was little affected at drug concentrations 100–1000 αM. The CAP was suppressed and its latency increased at concentrations >- 33 αM. Effects of suramin were largely reversible; those associated with cibacron blue and basilen blue generally were not. To the extent that these drugs acted selectively as antagonists of ATP receptor-mediated activity, results support the hypothesis that endogenous ATP exerts profound actions at the level of the cochlea and the auditory nerve.