INTENSITY AND FREQUENCY-CHARACTERISTICS OF PACINIAN CORPUSCLES .3. EFFECTS OF TETRODOTOXIN ON TRANSDUCTION PROCESS
INTENSITY AND FREQUENCY-CHARACTERISTICS OF PACINIAN CORPUSCLES .3. EFFECTS OF TETRODOTOXIN ON TRANSDUCTION PROCESS
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DOI：
10.1152/jn.1984.51.4.831
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发表时间：
1984-01-01
影响因子：
2.5
通讯作者：
BOLANOWSKI, SJ
中科院分区：
文献类型：
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作者：
BOLANOWSKI, SJ
河豚毒素（TTX）不仅影响猫肠系膜pacinian小体的再生动作电位，而且影响所测得的受体（产生器）电位。同时记录响应正弦位移刺激的细胞外受体电位和动作电位。用这种方法测得的受体电位响应的时间过程与驱动频率相似。由于动作电位的持续时间相对于高刺激频率下的周期周期较长，潜在的受体电位可能变得模糊。为了防止这种情况的发生，在6.0 μ m的浓度下进行了TTX的灌注。.apprx之后。30min时，神经尖峰完全消失，但受体电位幅度也有所下降。受体电位振幅与探针位移振幅相关的强度特征表明，无论刺激强度如何，TTX应用导致的幅度下降百分比都是恒定的。恒定响应准则的探头位移幅值与振动频率相关的频率特性表明，当应用TTX时，标准响应所需的位移幅值跨频率增加。增加是振动频率的幂函数。与感受器电位和探头位移之间的相位角与振动频率相关的频率特性随着TTX的应用而发生变化，这与幅频特性的变化一致。相位角随振动频率的变化呈u型函数。pacinian小体的接受膜对正弦位移的响应能力取决于振动频率，因此，小体的频率特性不能仅仅是小体片层被膜结构力学的函数。受体电位的一部分是由再生钠通道介导的，类似于那些涉及动作电位的产生，或者存在第三种类型的钠通道，虽然不是再生的，但能够促进分级反应，并且对TTX敏感。第三种可能是TTX可能破坏受体内的营养（调节剂）或传出机制。
Tetrodotoxin (TTX) affects not only regenerative action potentials but also the measured receptor (generator) potentials from cat mesentery pacinian corpuscles. Extracellularly recorded receptor and action potentials were simultaneously recorded in response to sinusoidal displacement stimuli. Receptor potentials measured in this manner responded with a time course similar to the driving freqency. Since the duration of the action potentials is long relative to the cycle period at high stimulus frequencies, the underlying receptor potentials can become obscured. To prevent this, TTX was applied through superfusion at a concentration of 6.0 .mu.M. After .apprx. 30 min, the neural spikes were fully eliminated but the receptor potentials were also decreased in amplitude. Intensity characteristics relating receptor-potential amplitudes to probe displacement amplitudes showed that the percentage decrease in amplitude due to the application of TTX was constant regardless of stimulus intensity. Frequency characteristics relating probe displacement amplitudes to vibration frequency for a constant-response criterion showed an increase in the displacement amplitude required for the criterion response, across frequency, when TTX was applied. The increase was a power function of vibration frequency. Frequency characteristics relating the phase angle between the receptor potential and probe displacement to vibration frequency showed changes with TTX application that were consistent with the changes found in the amplitude-frequency characteristics. The changes in phase angle followed a U-shaped function of vibration frequency. The ability of the receptive membrane of pacinian corpuscles to respond to sinusoidal displacements depends on vibration frequency and, thus, the corpuscle''s frequency characteristics cannot be a function of the mechanics of the lamellar capsule structure of the corpuscle alone. A portion of the receptor potential is mediated by regenerative Na channels similar to those implicated in the generation of action potentials or there exists a 3rd type of Na channel which, while not regenerative, is capable of contributing toward a graded response and is TTX sensitive. A 3rd possibility is that TTX may disrupt trophic (modulator) or efferent mechanisms within the receptor.