Eustachian Tube Function in the Chinchilla

Abstract

\s=b\Eustachian tube function (ETF) was evaluated in 22 ears of 18 chinchillas using the inflation-deflation and forcedresponse protocols. The results of the ETF tests showed an unusual function in the chinchilla. Of the 22 tests, one indicated a patulous eustachian tube (ET) and 20 suggested a semipatulous ET. This was evidenced by a passive, pressure\x=req-\ dependent, complete reduction of applied positive or negative ME pressures in these ears. This phenomenon has no counterpart in the ETF of rhesus monkeys or humans. Discrete changes in the continual leakage of applied pressures, indicative of active tubal dilation, were only observed during tests in four ears. Passive tubal resistance was similar to that of humans, though all values were characterized by large variances. Active tubal resistance could only be defined for four of the test ears. The ET of eight ears constricted with swallowing. In nine test ears, neither constriction nor dilation was observed during the forced-response test, and four tests showed dilation of the ET with swallowing. These results show that the ETF of the chinchilla is radically different from that of humans or monkeys. (Arch Otolaryngol 1985;111:305-308)

Otologic and systemic manifestations of experimental influenza a virus infection in the ferret

“…1° However, normal tubal function in the chinchilla is quite different from that in ferrets and human beings, making comparison difficult. 12 The fact that OM was not seen in this study is in contrast to findings reported for previous human viral challenges. Although uncommon, OM has been observed in a small proportion of adult volunteers experimentally infected with rhinovirus-39 (3%) 5 and influenza A virus (19%).…”

Gentamicin uptake in the chinchilla inner ear

“…Three mechanisms could lead to the transfer of a unilaterally applied substance to the contralateral inner ear. One is transmission via the Eustachian tube, which is continuously open in the chinchilla model (Doyle, 1985). This mode of transmission is less likely, as transfer to the contralateral ear occurs with micropump application of gentamicin to the round window at low rates.…”

A Mutation in the sap Operon Attenuates Survival of Nontypeable Haemophilus influenzae in a Chinchilla Model of Otitis Media

“…It has been determined that gas exchange can occur both into and out of the middle ear cavity via the eustachian tube and also by passive diffusion across the middle ear mucosa (22,53). Furthermore, the chinchilla eustachian tube appears to be continually semipatulous where a constant airflow may be maintained by the passage of air into the middle ear cleft (15). The presence of an air-fluid interface in the chinchilla bulla 7 days after infection still allows gas exchange through the middle ear mucosa (29).…”