[Motility of the vestibular hair cell of the guinea pig and bull frog].
The motile response of the isolated vestibular hair cell induced by a neurotransmitter was studied. After application of both physostigmine and acetylcholine (Ach) as well as glutamic acid, shortening or tilting of the neck of the guinea pig hair cell was observed. These findings suggest that the effect of a neurotransmitter in the neck region as well as the efferent neuron is involved in the motile response. The location of F-action in isolated vestibular hair cells was investigated by using FITC-labeled phalloidin. In freeze-fixed vestibular hair cells, marked labeling was noted in the hair bundle, cuticular plate and throughout the cytoplasm. After application of both physostigmine and Ach, the labeling in the cuticular plate and the cytoplasm became more intense than that in the hair bundle. Alteration of this phalloidin-labeling pattern suggests that actin could play an important role in the self movement of vestibular sensory cells. The shape of the bull frog hair cell also changed after application of Ach. At the same time, spontaneous discharge and the time constant of the posterior semicircular canal nerve activity decreased. These results suggest that an adaptation mechanism induced by change in the cell shape and membrane potential inhibits the activity of the afferent neuron. Furthermore, these active events could be closely related to the active regulation of vestibular hair cell transmission.
Tanigawa
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Department of Otolaryngology, Hiroshima University School of Medicine.
D000109:Acetylcholine / Q000494:pharmacology; D000199:Actins / Q000502:physiology; D000818:Animals; D002465:Cell Movement / Q000502:physiology; D006168:Guinea Pigs; D018069:Hair Cells, Vestibular / Q000502:physiology*; D066298:In Vitro Techniques; D018377:Neurotransmitter Agents / Q000502:physiology*; D010830:Physostigmine / Q000494:pharmacology; D011892:Rana catesbeiana
D000199:Actins; D018377:Neurotransmitter Agents; D010830:Physostigmine; D000109:Acetylcholine