Observations of intracellular Ca^<2+> and Cl-concentrations in inner ear isolated cells

1)为阐明耳蜗毛细胞和前庭毛细胞的传出抑制机制，测定了候选传出神经递质对豚鼠耳蜗毛细胞和前庭毛细胞内钙离子浓度([Ca^&lt；2+&gt；]i)的影响。Ach和ATP似乎都是传出神经递质，但CGRP和Enk被认为是传出神经调节剂。2)耳蜗外毛细胞的缓慢缩短被认为是改变耳蜗敏感度的原因。强电场刺激豚鼠分离的外毛细胞可使细胞缩短2-3分钟。电刺激使细胞长度和体积减小，细胞内氯离子浓度降低。3)用敏感的荧光染料Fura-2对豚鼠耳蜗单离螺旋神经节细胞(SGCs)进行了[Ca~(2+)]i测定。L-古塔米特可使神经突起的SGCs[Ca~(2+)]i升高。因此，我们认为兴奋性氨基酸可能是豚鼠耳蜗毛细胞传入神经突触的神经递质。

1) To elucidate efferent inhibitory mechanisms of the cochlear hair cells and vestibular hair cells, the effects of candidate efferent neurotransmitters on intracellular Ca^<2+> concentrations ([Ca^<2+>] i) in these isolated cells of guinea pig were determined. Both Ach and ATP seem to be efferent neurotransmitters, however, CGRP and Enk were thought to be functioning as efferent neuromodulators.2) Slow shortening of cochlear outer hair cells has been speculated to modify cochlear sensitivity. Tetanic electrical field stimulation of isolated outer hair cells from guinea pigs shortened the cells for 2-3 min. Electrical stimulation reduced cell length and volume and decreased the intracellular Cl-concentration. These findings suggest that these shortening and shrinkage result from Cl- efflux.3) [Ca^<2+>] i is isolated spiral ganglion cells (SGCs) of the guinea pig cochlear were measured using the Ca^<2+> sensitive fluorescence dye fura-2. L-gultamate increased [Ca^<2+>] i in SGCs with neuritic processes. We thus propose that the excitatory amino acid, probably L-gultamate, may function as a neurotransmitter of the hair cell-afferent nerve synapse in the guinea pig cochlea.