title: Cholinergic agonists increase intracellular calcium concentration in guinea pig vestibular hair cells.
abstract: OBJECTIVE
  To better understand the cholinergic receptors in vestibular hair cells (VHC) and their subtypes, and to investigate the effects of cholinergic agonists on intracellular calcium concentration ([Ca2+]i) in guinea pig VHCs.
  
  
  METHODS
  VHCs were isolated from guinea pig crista ampullaris by enzymatic and mechanical methods. The effect of cholinergic agonists on [Ca2+]i was examined using laser scanning confocal microscopy and the Ca2+ sensitive dye Fluo-3.
  
  
  RESULTS
  The results showed that the addition of acetylcholine (ACh) and carbachol (CCh), muscamic and nicotinic agonists, induced [Ca2+]i increases in all the VHCs, whereas acetylcholine bromide (ACh-Br), a nicotinic agonist, induced the [Ca2+]i increase in only a small percentage of VHCs. The ACh or CCh-induced Ca2+ response could be partially suppressed by atropine. In the presence of 0.1 mmol/L atropine, the amplitudes of ACh or CCh-induced [Ca2+]i responses became significantly smaller than those in atropine free medium (P < 0.01).
  
  
  CONCLUSIONS
  The results suggest the existence of cholinergic receptors in guinea pig VHCs. It is the muscamic agonists rather than nicontic receptors that dominate [Ca2+]i variation. Atropine can suppress muscamic agonist-induced Ca2+ responses.
authors.affiliation: Department of Otolaryngology, Head and Neck Surgery, General Hospital of PLA, Beijing 100853, China. hanweiju@bj.col.com.cn
authors.forename: W
authors.initials: W
authors.lastname: Han
authors.forename: S
authors.initials: S
authors.lastname: Zhang
authors.forename: D
authors.initials: D
authors.lastname: Han
authors.forename: S
authors.initials: S
authors.lastname: Jiang
authors.forename: W
authors.initials: W
authors.lastname: Yang
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002217:Carbachol / Q000494:pharmacology; D018679:Cholinergic Agonists / Q000494:pharmacology*; D006168:Guinea Pigs; D018069:Hair Cells, Vestibular / Q000187:drug effects* / Q000378:metabolism
chemical_list: D018679:Cholinergic Agonists; D001285:Atropine; D002217:Carbachol; D000109:Acetylcholine; D002118:Calcium