Gentamicin uptake in the chinchilla inner ear

Preclinical and Clinical Studies of Unrelieved Aural Fullness following Intratympanic Gentamicin Injection in Patients with Intractable Ménière's Disease

“…Further study revealed there was no significant difference in GTTR labeling in the dark cells among different time points following intratympanic injection. In the present study, the GTTR labeling in the ampullar dark cells is consistent with the results of the study of Schmid et al [2011], which used the acutely isolated inner ear of the rat that had been exposed to GTTR for 10 min, but is not consistent with the results of the study of Roehm et al [2007], which observed substantial autoradiographic deposits for tritiated gentamicin in dark cells within the utricle.…”

“…Although a few clinical studies demonstrated that aural fullness can be reduced following intratympanic gentamicin administration, the evidence was based only on subjective evaluation [Sala, 1997; McFeely et al, 1998], and animal studies have yielded incomplete data [Harner et al, 1998; Roehm et al, 2007]. Therefore, further data on clinical outcomes and basic scientific investigation are required to establish the effectiveness of using intratympanic gentamicin to relieve aural fullness.…”

“…Previous studies on the effects of gentamicin on dark cells remain unclear. Roehm et al [2007], using autoradiography of tritiated gentamicin, reported that utricular dark cells rapidly took up gentamicin following intratympanic injection and retained it within the cell body while staining levels fell to background levels in the rest of the injected ear over 14 days [Roehm et al, 2007]. Pender [1985] observed dark cell death in the vestibular end-organs following gentamicin tympanolysis.…”

Prospective Electrophysiologic Findings of Round Window Stimulation in a Model of Experimentally Induced Stapes Fixation

“…Both humans and chinchillas possess a cochleovestibular nerve that presents as a possible pathway for pressure transmission. Another possibility is the cochlear aqueduct, a channel connecting the perilymph with CSF, which is patent in chinchillas (59). Debate exists, however, whether the aqueduct is open in humans because studies have demonstrated variable patency.…”

Critical Roles of Transitional Cells and Na/K-ATPase in the Formation of Vestibular Endolymph

“…Such long latencies may reflect the time required for channel antagonists to accumulate to an efficient level in the cyst lumen. The pathways by which antagonists may enter the endolymph remain mostly unknown, apart for aminoglycoside entry; dark cells may be involved, since they take up transtympanically administered gentamicin (Roehm et al, 2007). Whereas aminoglycoside action as a transduction channel permeant blocker (Kroese et al, 1989;Gale et al, 2001;Géléoc and Holt, 2003) is consistent with the enhancement of [K ϩ ]ec, the contribution of aminoglycoside ototoxicity should also be considered.…”