Spikes and membrane potential oscillations in hair cells generate periodic afferent activity in the frog sacculus.
Spikes and membrane potential oscillations in hair cells generate periodic afferent activity in the frog sacculus.
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DOI：
10.1523/jneurosci.1798-09.2009
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发表时间：
2009-08-12
期刊：
影响因子：
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通讯作者：
Roberts WM
中科院分区：
文献类型：
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作者：
Rutherford MA;Roberts WM
为了寻找可能有助于耳朵感觉编码或放大的膜电位振荡，我们对移植青蛙球囊中的毛细胞和突触后传入神经突进行了全细胞和穿孔贴片记录，并阻断了机电转导（MET）。小去极化保持电流可替代体内静息 MET 电流，在 37% 的测试毛细胞中诱发全或无钙尖峰（39 –75 mV 振幅），并在另外 14% 的细胞中诱发连续膜电位振荡（14 –28 mV；15–130 Hz）。尖峰毛细胞平均比非尖峰毛细胞更高、更薄，并且通过延迟整流通道 (IKV) 和非失活钙激活钾通道 (IBK，稳定) 的外向电流较小，而内向整流电流 (IK1) 较大。一些尖峰毛细胞在当前步骤开始时仅发射短暂的序列，但其他毛细胞可以维持重复发射（3-70 Hz）。部分阻断 IBK 改变了振荡和尖峰的幅度和频率，并将一些非尖峰细胞转化为尖峰细胞。振荡毛细胞优先放大接近其自然振荡频率的正弦刺激。突触后记录显示一些传入神经突中有规律定时的 EPSP 爆发。 EPSP 爆发能够触发传入尖峰，这可能是在位于传入轴突最外周髓磷脂段附近的钠通道簇处启动的。这些结果表明，一些青蛙囊毛细胞可以产生自发的节律活动，这可能驱动传入轴突的周期性背景活动。
To look for membrane potential oscillations that may contribute to sensory coding or amplification in the ear, we made whole-cell and perforated-patch recordings from hair cells and postsynaptic afferent neurites in the explanted frog sacculus, with mechanoelectrical transduction (MET) blocked. Small depolarizing holding currents, which may serve to replace the in vivo resting MET current, evoked all-or-none calcium spikes (39 –75 mV amplitude) in 37% of hair cells tested, and continuous membrane potential oscillations (14 –28 mV; 15–130 Hz) in an additional 14% of cells. Spiking hair cells were on average taller and thinner than nonspiking hair cells, and had smaller outward currents through delayed rectifier channels (IKV ) and noninactivating calcium-activated potassium channels (IBK,steady), and larger inward rectifier currents (IK1 ). Some spiking hair cells fired only a brief train at the onset of a current step, but others could sustain repetitive firing (3–70 Hz). Partial blockade of IBK changed the amplitude and frequency of oscillations and spikes, and converted some nonspiking cells into spiking cells. Oscillatory hair cells preferentially amplified sinusoidal stimuli at frequencies near their natural oscillation frequency. Postsynaptic recordings revealed regularly timed bursts of EPSPs in some afferent neurites. EPSP bursts were able to trigger afferent spikes, which may be initiated at the sodium channel cluster located adjacent to the afferent axon’s most peripheral myelin segment. These results show that some frog saccular hair cells can generate spontaneous rhythmic activity that may drive periodic background activity in afferent axons.