Measurement of intracellular free Ca2+ concentration in guinea pig spiral ganglion cells.
Intracellular free Ca2+ concentration ([Ca2+]i) in spiral ganglion cells (SGC) of guinea pig was measured using the fura-2 fluorescence method. Application of high-K+ external solution increased [Ca2+]i. [Ca2+]i elevation was suppressed by either depletion of external Ca2+ or application of the dihydropyridine Ca2+ channel antagonist, nicardipine. One of the putative hair cell afferent nerve neurotransmitters, L-glutamate (Glu), induced [Ca2+]i elevation in SGC. Pharmacological studies suggested that the Glu receptor may be a non-NMDA subtype. Glu-induced response was suppressed by either depletion of external Ca2+ or application of nicardipine, indicating that Glu-induced [Ca2+]i elevation is mainly carried out by the voltage-dependent Ca2+ channel in SGC.
Shimozono
M
M
Department of Otorhinolaryngology, Miyazaki Medical College, Japan.
Tono
T
T
Morimitsu
T
T
Nakagawa
T
T
Komune
S
S
D000818:Animals; D002118:Calcium / Q000032:analysis* / Q000502:physiology; D015220:Calcium Channels / Q000187:drug effects; D003051:Cochlea / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D016257:Fura-2; D018698:Glutamic Acid / Q000494:pharmacology; D006168:Guinea Pigs; D009529:Nicardipine / Q000494:pharmacology; D013136:Spiral Ganglion / Q000737:chemistry* / Q000502:physiology; D013997:Time Factors
D015220:Calcium Channels; D018698:Glutamic Acid; D009529:Nicardipine; D002118:Calcium; D016257:Fura-2