Glutamate-induced intracellular Ca2+ elevation in isolated spiral ganglion cells of the guinea pig cochlea.
Intracellular calcium concentrations ([Ca2+]i) in acutely isolated spiral ganglion cells (SGCs) of the guinea pig cochlea were measured using digital imaging microscopy and the Ca(2+)-sensitive fluorescence dye fura-2. L-glutamate increased [Ca2+]i in SGCs with neuritic processes but did not lead to an increase in [Ca2+]i in SGCs without neuritic processes. The depolarization induced by high K+ (150 mM) solution increased [Ca2+]i in both SGCs, with and without neuritic processes. The L-glutamate-induced [Ca2+]i elevation was abolished in the absence of extracellular Ca2+. We thus propose that the increase of [Ca2+]i during L-glutamate stimulation is mainly related to an influx of extracellular Ca2+. The excitatory amino acids, probably L-glutamate, may function as a neurotransmitter of the hair cell-afferent nerve synapse in the guinea pig cochlea.
Harada
N
N
Department of Otolaryngology, Kansai Medical University, Osaka, Japan.
Han
D Y
DY
Komeda
M
M
Yamashita
T
T
D000818:Animals; D002118:Calcium / Q000032:analysis* / Q000502:physiology; D003051:Cochlea / Q000166:cytology*; D003238:Connective Tissue; D046508:Culture Techniques; D016257:Fura-2; D018698:Glutamic Acid / Q000032:analysis / Q000502:physiology; D006168:Guinea Pigs; D006198:Hair Cells, Auditory / Q000502:physiology; D008853:Microscopy; D016194:Receptors, N-Methyl-D-Aspartate / Q000502:physiology; D013136:Spiral Ganglion / Q000166:cytology*
D016194:Receptors, N-Methyl-D-Aspartate; D018698:Glutamic Acid; D002118:Calcium; D016257:Fura-2