Effects of lidocaine on basilar membrane vibration in the guinea pig.
The effects of lidocaine on basilar membrane (BM) vibration and compound action potential (CAP) were studied in guinea pigs in order to elucidate the site of lidocaine action in the cochlea. BM vibration was measured with a laser Doppler vibrometer through an opening made in the lateral bony wall of the scala tympani at the basal turn. Ten min after local administration of lidocaine (250 microg) into the scala tympani, the velocity of BM vibration and the CAP amplitude decreased significantly at around the characteristic frequency of the stimulus sound (p < 0.05). The maximum decreases were 4 dB in the velocity of the BM vibration and 40 dB in the CAP amplitude. In contrast, such changes were not observed after i.v. injection of lidocaine (1.5 mg/kg). These results suggest that when lidocaine is administered locally in the cochlea it acts not only on the cochlear nerve but also on the outer hair cells.
Maruyama
J
J
Department of Otolaryngology, Ehime University School of Medicine, Onsen-gun, Japan. junmaru@m.ehime-u.ac.jp
Kobayashi
T
T
Sugimoto
A
A
Gyo
K
K
D000287:Administration, Topical; D000779:Anesthetics, Local / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D001300:Audiometry, Evoked Response; D001489:Basilar Membrane / Q000187:drug effects*; D003051:Cochlea / Q000187:drug effects; D006168:Guinea Pigs; D018072:Hair Cells, Auditory, Outer / Q000187:drug effects; D008012:Lidocaine / Q000008:administration & dosage / Q000494:pharmacology*; D017084:Otoacoustic Emissions, Spontaneous / Q000187:drug effects; D013016:Sound; D014732:Vibration
D000779:Anesthetics, Local; D008012:Lidocaine