Xi X, Jiang S C
Institute of Otolaryngology, General Hospital of PLA, Beijing.
Sheng Li Xue Bao. 1995 Apr;47(2):105-10.
Effects of acetylcholine (ACh) and ATP as the candidates of efferent neurotransmitter on intracellular Ca2+ concentrations ( [Ca2+]i) of the isolated outer hair cells (OHCs) from guinea pig cochlea were studied with laser scanning confocal microscope. The OHCs were loaded with Ca2+ sensitive dye Fluo-3, whose fluorescent intensity was strongest at the basal end in resting OHC. The presence of ACh gradually increased [Ca2+]i to a higher level at the basal end of OHCs. Continuous application of ATP caused a rapid [Ca2+]i increase followed by a gradual exhaustion throughout the whole OHC. Magnitude of the increase at the apex was greater than that at the base. In OHCs whose calcium had been exhausted by ATP, ACh induced a temporary increase in [Ca2+]i. It seems likely that the ACh-induced [Ca2+]i rise is partly due to an influx of extracellular Ca2+. The bursting nature of ATP-induced [Ca2+]i rise may be a consequence of Ca2+ influx through the ATP-gated cation channels and of the mobilization of intracellular store mediated by ATP.
采用激光扫描共聚焦显微镜研究了作为传出神经递质候选物的乙酰胆碱（ACh）和ATP对豚鼠耳蜗孤立外毛细胞（OHC）细胞内钙离子浓度（[Ca2+]i）的影响。用钙离子敏感染料Fluo-3加载OHC，在静息OHC中其荧光强度在基底端最强。ACh的存在使OHC基底端的[Ca2+]i逐渐升高至更高水平。持续应用ATP导致[Ca2+]i迅速升高，随后在整个OHC中逐渐耗尽。顶端的升高幅度大于基部。在ATP使钙离子耗尽的OHC中，ACh诱导[Ca2+]i暂时升高。ACh诱导的[Ca2+]i升高似乎部分归因于细胞外钙离子的内流。ATP诱导的[Ca2+]i升高的爆发性质可能是钙离子通过ATP门控阳离子通道内流以及ATP介导的细胞内钙库动员的结果。
