Exocytosis in the frog amphibian papilla.
Exocytosis in the frog amphibian papilla.
复制标题
青蛙两栖动物乳头的胞吐作用。
DOI：
10.1007/s10162-011-0304-1
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发表时间：
2012
期刊：
影响因子：
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通讯作者：
Narins,PeterM
中科院分区：
文献类型：
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作者：
Quiñones,PatriciaM;Luu,Cindy;Schweizer,FelixE;Narins,PeterM
利用全细胞膜片钳记录，我们测量了豹蛙两栖动物乳头（AP）两个毛细胞亚群的膜电容变化（ΔCm）：低频（100-500 Hz），吻侧毛细胞和高频（500-1200 Hz），尾侧毛细胞，以研究胞外分泌的张力差异。吻侧毛细胞和尾侧毛细胞的去极化均诱发了类似振幅的强健ΔCmresponses。然而，钙的释放依赖性，即ΔCmrelative与钙内流量（QCa2+）之间的关系，在吻侧毛细胞中是线性的，而在尾侧毛细胞中是超线性的。此外，在尾毛细胞活动区释放的囊泡数量较多，表明尾毛细胞胞吐的时间精度增加。ΔCmresponses也获得了对不同频率的正弦刺激的响应，但吻侧和尾侧毛细胞ΔCmrevealed没有任何频率选择性。虽然所有AP毛细胞都表达otoferlin和synaptotagmin IV (SytIV)，但我们获得了钙缓冲calretinin的张力分布的证据，这可能进一步提高毛细胞突触水平的时间分辨率。我们的研究结果表明，低频率（吻侧）和高频率（尾侧）的毛细胞应用不同的机制来微调胞吐。
Using whole-cell patch-clamp recordings, we measured changes in membrane capacitance (ΔCm) in two subsets of hair cells from the leopard frog amphibian papilla (AP): the low-frequency (100–500 Hz), rostral hair cells and the high-frequency (500–1200 Hz), caudal hair cells, in order to investigate tonotopic differences in exocytosis. Depolarizations of both rostral and caudal hair cells evoked robust ΔCmresponses of similar amplitude. However, the calcium dependence of release, i.e., the relationship between ΔCmrelative to the amount of calcium influx (QCa2+), was found to be linear in rostral hair cells but supra-linear in caudal hair cells. In addition, the higher numbers of vesicles released at caudal hair cell active zones suggests increased temporal precision of caudal hair cell exocytosis. ΔCmresponses were also obtained in response to sinusoidal stimuli of varying frequency, but neither rostral nor caudal hair cell ΔCmrevealed any frequency selectivity. While all AP hair cells express both otoferlin and synaptotagmin IV (SytIV), we obtained evidence of a tonotopic distribution of the calcium buffer calretinin which may further increase temporal resolution at the level of the hair cell synapse. Our findings suggest that the low (rostral) and high (caudal) frequency hair cells apply different mechanisms for fine-tuning exocytosis.