Yamashita T, Amano H, Kumazawa T
Department of Otolaryngology, Kansai Medical University, Osaka, Japan.
ORL J Otorhinolaryngol Relat Spec. 1993 Jul-Aug;55(4):201-4. doi: 10.1159/000276422.
To elucidate efferent inhibitory mechanisms of the cochlear inner hair cells (IHCs), the effects of candidate efferent neurotransmitters on intracellular Ca2+ concentrations ([Ca2+]i) in the isolated IHCs of guinea pig were determined using the Ca2+ sensitive dye fura-2 and digital imaging microscopy. In the presence of 1 mM acetylcholine (ACh), there was a gradual and reversible increase in [Ca2+]i. In the presence of 10 microM ATP, there was a rapid and marked rise in [Ca2+]i. Thus, both ACh and ATP seem to be efferent neurotransmitters in IHCs of guinea pig. The ATP-induced elevation of [Ca2+]i in IHCs was suppressed when ACh was concomitantly applied; therefore, ACh may act as an antagonist of ATP-induced Ca2+ entry. With the independent addition of 10 microM calcitonin gene-related peptide and 10 microM enkephalin, there were no significant increases in [Ca2+]i. These neuropeptides are putative candidates for the efferent neuromodulators in IHCs of the guinea pig.
为了阐明耳蜗内毛细胞（IHC）的传出抑制机制，我们使用钙敏感染料fura-2和数字成像显微镜，测定了候选传出神经递质对豚鼠离体IHC细胞内钙离子浓度（[Ca2+]i）的影响。在1 mM乙酰胆碱（ACh）存在的情况下，[Ca2+]i逐渐且可逆地增加。在10 μM ATP存在的情况下，[Ca2+]i迅速且显著升高。因此，ACh和ATP似乎都是豚鼠IHC中的传出神经递质。当同时应用ACh时，ATP诱导的IHC中[Ca2+]i升高受到抑制；因此，ACh可能作为ATP诱导的钙离子内流的拮抗剂。单独添加10 μM降钙素基因相关肽和10 μM脑啡肽时，[Ca2+]i没有显著增加。这些神经肽被认为是豚鼠IHC中传出神经调质的候选者。
