title: Distribution of Ca2+ channels on cochlear outer hair cells revealed by fluorescent dihydropyridines.
abstract: Physiological evidence has shown that cochlear outer hair cells (OHC) possess L-type voltage-dependent Ca2+ channels through which Ca2+ enters the OHC during depolarization. Their subcellular distribution has, however, remained unclear. In this study, the distribution of L-type Ca2+ channels on the basolateral plasma membrane of OHC has been demonstrated by the use of a laser scanning confocal microscope (LSCM) and a fluorescent probe DMBODIPY-DHP. The fluorescent staining pattern on the basolateral wall is nonuniform, suggesting a heterogeneous distribution of the channels in the plasma membrane. Direct imaging of intracellular Ca2+ visualized in real time by means of the LSCM and the fluorescent Ca2+ probe fluo 3 revealed temporal and spatial integration of Ca2+ movements and Ca2+ channel distribution. Exposure to high-K+ solution induced heterogeneity in the subcellular increase in the intracellular Ca2+ concentration. These results suggest that the heterogeneous distribution of L-type Ca2+ channels on the basolateral membrane might induce heterogeneous intracellular Ca2+ distribution during electrical activity in the OHC.
authors.affiliation: Department of Otolaryngology, Tohoku University School of Medicine, Sendai, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Oshima
authors.forename: K
authors.initials: K
authors.lastname: Ikeda
authors.forename: M
authors.initials: M
authors.lastname: Furukawa
authors.forename: N
authors.initials: N
authors.lastname: Ueda
authors.forename: H
authors.initials: H
authors.lastname: Suzuki
authors.forename: T
authors.initials: T
authors.lastname: Takasaka
mesh_terms: D000818:Animals; D015220:Calcium Channels / Q000032:analysis* / Q000378:metabolism; D004095:Dihydropyridines; D005260:Female; D005456:Fluorescent Dyes; D006168:Guinea Pigs; D006198:Hair Cells, Auditory / Q000378:metabolism*; D010627:Phenethylamines
chemical_list: C089792:1,4-dihydro--2,6-dimethyl-4-(2-trifluoromethylphenyl)-3,5-pyridinedicarboxylic acid 2-(4,4-difluoro-5,7-dimethyl-4-bora-3a,4a-diaza-3-(s-indacene)propionylamino)ethylethyl ester; D015220:Calcium Channels; D004095:Dihydropyridines; D005456:Fluorescent Dyes; D010627:Phenethylamines