Properties of cholinergic receptor-mediated ion channels on type I vestibular hair cells of guinea pigs.
- Author:
Yun ZHU
1
;
Wei-Jia KONG
;
Jiao XIA
;
Yu ZHANG
;
Hua-Mao CHENG
;
Chang-Kai GUO
Author Information
1. Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China.
- Publication Type:Journal Article
- MeSH:
Acetylcholine;
pharmacology;
Animals;
Guinea Pigs;
Hair Cells, Vestibular;
physiology;
Membrane Potentials;
Patch-Clamp Techniques;
Potassium Channel Blockers;
pharmacology;
Potassium Channels, Calcium-Activated;
physiology;
Receptors, Cholinergic;
physiology
- From:
Acta Physiologica Sinica
2008;60(3):375-381
- CountryChina
- Language:Chinese
-
Abstract:
To confirm the existence of cholinergic receptors on type I vestibular hair cells (VHCs I) of guinea pigs and to study the properties of the cholinergic receptor-mediated ion channels on VHCs I, electrophysiological responses of isolated VHCs I to external ACh were examined by means of whole-cell patch-clamp recordings. The results showed that 7.5% (21/279) VHCs I were found to be sensitive to ACh (10-1000 μmol/L). ACh generated an outward current in a steady, slow, dose-dependent [EC(50) was (63.78±2.31) μmol/L] and voltage-independent manner. In standard extracellular solution, ACh at the concentration of 100 μmol/L triggered a calcium-dependent current of (170±15) pA at holding potential of -50 mV, and the current amplitude could be depressed by extracellularly added calcium-dependent potassium channel antagonist TEA. The time interval for the next complete activation of ACh-sensitive current was no less than 1 min. The ion channels did not shut off even when they were exposed to ACh for an extended period of time (8 min). The results suggest that dose-dependent, calcium-dependent and voltage-independent cholinergic receptors were located on a few of the VHCs I investibular epithelium of guinea pigs. The cholinergic receptors did not show desensitization to ACh. This work reveals the existence of efferent neurotransmitter receptors on VHCs I and helps in understanding the function of vestibular efferent nervous system, and may provide some useful information on guiding the clinical rehabilitative treatment of vertigo.
