1993 Fiscal Year Final Research Report Summary
Basic mechanism of caloric response using isolated frog labyrinth
| Project/Area Number |
04671042
|
|---|
| Research Category |
Grant-in-Aid for General Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Research Field |
Otorhinolaryngology
|
|---|
| Research Institution | HIROSHIMA UNIVERSITY |
|---|
Principal Investigator |
SUZUKI Mamoru Hiroshima University School of Medicine Associate Professor, 医学部, 助教授 (80116607)
|
|---|
| Project Period (FY) |
1992 – 1993
|
| Keywords | Caloric response / Semicircular canal / Action potential / Utricle / Ototoxic drug / Thermocomvective flow / Bull frog |
|---|
| Research Abstract |
Basic mechanism of caloric response was studied using isolated bull frog semicircular canal and utricle. First, the membranous labylinth was en bloc removed to study dynamic transduction of the endolymphatic flow. When the anterior canal was stimulated, an excitatory action potential was evoked from the anterior amullary nerve. At the same time, an inhibitory response was induced through the posterior nerve. Therefore, the endolymphatic flow applied to a part of the labyrinth leads to a systemic fluid shift in other organ through dynamic transduction. When an aminoglycoside drug was added to the perilymphatic space of the posterior semicircular canal, the action potential was inhibited. Therefore, ionic environment of the perilymph is essential for maintaining a function of the vestibular sensory cell. Finally, the semicircular canal and utricle were stimulated by thermoconvection, since caloric response is induced by thermoconvective fluid flow in the endolymph. Frozen Ringer's solution was used to produce thermoconvective flow along the gravitational plane. When a semicircular canal was stimulated by thermoconvection, excitatory and inhibotory responses were observed according to the direction of the thermoconvection. Therefore, thermoconvective flow serves as a valid mechanical stimulus to the sensory cells. When the utricle was stimulated by thermoconvection with different directions, the responses were the same regardless of the stimuli. This indicates that the utricle has an equal directional excitability, thus might be most influenced by weightless condition.
|
