Effects of MRI contrast agents (Omniscan) on vestibular end organs.
CONCLUSIONS
These findings indicate that application of 4-16-fold diluted Omniscan could have depressant effects on the frog vestibular end organs. Based on cochlear studies on cytotoxicity using 8-fold diluted Omniscan, 16-fold diluted Omniscan is optimal for the inner ear and its application could be useful for visualization of endolymphatic hydrops as well as the control of vertiginous attacks in Meniere's disease.


OBJECTIVE
Endolymphatic hydrops could be visualized recently by intratympanic injection of Omniscan diluted 8- or 16-fold with saline using three-dimensional fluid attenuated inversion recovery (3-D FLAIR) MRI. However, the effects of the Omniscan on vestibular end organs are not clearly understood. The purpose of this study was to investigate the effects of Omniscan on vestibular end organs both morphologically and physiologically.


METHODS
Vestibular hair cells isolated from bullfrogs were loaded with 4-32-fold diluted Omniscan (gadolinium hydrate) and morphological changes were observed. Moreover, compound action potentials of posterior semicircular canals were also observed after application of Omniscan.


RESULTS
Application of 4-16-fold diluted Omniscan caused morphological damage of isolated vestibular hair cells and decreased action potentials of the posterior semicircular canal. After application of 32-fold diluted Omniscan, no apparent changes were noted even after 20 min, both morphologically and physiologically.
Tanaka
Hirokazu
H
Department of Otolaryngology, Aichi Medical University, Aichi, Japan.
Tanigawa
Tohru
T
Suzuki
Mamoru
M
Otsuka
Koji
K
Inafuku
Shigeru
S
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D003287:Contrast Media / Q000633:toxicity*; D004305:Dose-Response Relationship, Drug; D019786:Gadolinium DTPA / Q000633:toxicity*; D018069:Hair Cells, Vestibular / Q000187:drug effects* / Q000473:pathology; D009994:Osmolar Concentration; D011892:Rana catesbeiana; D012665:Semicircular Canals / Q000187:drug effects* / Q000473:pathology; D012815:Signal Processing, Computer-Assisted; D014725:Vestibular Nerve / Q000187:drug effects
D003287:Contrast Media; C064925:gadodiamide; D019786:Gadolinium DTPA