QUANTITATIVE-ANALYSIS OF LARYNGEAL MECHANOSENSITIVITY IN THE CAT AND RABBIT
QUANTITATIVE-ANALYSIS OF LARYNGEAL MECHANOSENSITIVITY IN THE CAT AND RABBIT
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DOI：
10.1113/jphysiol.1987.sp016625
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发表时间：
1987-07-01
影响因子：
5.5
通讯作者：
NAIL, BS
中科院分区：
文献类型：
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作者：
DAVIS, PJ;NAIL, BS
在麻醉、麻痹猫(148根)和兔(58根)喉上神经内支中，发现单个传入纤维对光接触或轻轻探查开放喉部暴露的上皮区有反应。使用伺服控制的机械刺激器，定量检测这些喉部机械感受器对静态(阶梯压痕)和动态(振动)形式的机械刺激的敏感性。在两个物种中都观察到了两类主要的机械感受器(Boushey，Richardson，Widdicombe和Wise，1974)。其中一类是在10-70赫兹的频率下有规律和连续的活动模式(紧张性纤维，猫为66，兔为35)。另一类是静默的，或者(更罕见的)以非常低的频率不规则地活动(静默的纤维，猫有82根，兔子有23根)。感受野的位置是通过人工探测确定的。观察到这两类纤维在接受野位置上的种间和区域差异。用预触发平均法测定了21条强直性纤维和7条静止性纤维的传导速度。所获得的结果(紧张：范围10.8-30.0，平均+-。SEE平均值为21.4。+-。1.2米/S；无声：14.8-28.6，20.4+-。1.8m/S)是第III类传入纤维的特征，但在两类传入纤维中差异不显著。这两类受体在与它们的感受野相对应的粘膜区域的阶梯状凹陷开始时都显示出反应。在这一短暂的初步反应之后，这两个阶层的行为明显不同。紧张性纤维总是缓慢适应，而大多数(猫55条中的44条；兔子的23条中的22条)沉默的纤维迅速适应，至少是适应较小的凹陷幅度。当探针刺激器在感受区上振动0.5或1.0时，两类受体都很容易以与探针刺激器相同的频率(1：1夹带)放电。调谐曲线是在不同频率下在整个测试期间引起1：1夹带所需的最小幅度。这两个类别中的单个纤维可以在高达400赫兹或更高的频率下以敏感的(例如<；100微米)振动幅度被夹带。然而，所有的纤维在这些较高的频率上都比在频率范围内的较低的点更不敏感。快速适应后，无声纤维的曲线通常显示出可识别的最小值(10-60赫兹)，但这些曲线或这些曲线以及其他无声纤维的调谐相对较宽。慢慢适应，沉默的纤维在较低的频率范围内具有特别平坦的曲线。紧张性纤维的曲线在接近其自发放电率的较低频率时也更敏感，但通常不能在低于此频率的频率下被“刺激”放电。结论是，来自不同位置的纤维的动态敏感性将确保异物颗粒以最快的速度和在大多数喉部表面移动到喉部的高概率。
Single afferent fibres in the internal branch of the superior laryngeal nerve which responded to light touch or gentle probing of discrete areas of the exposed epithelium of the opened larynx were identified in anaesthetized, paralysed cats (148 fibres) and rabbits (58 fibres). A quantitative examination of the sensitivity of these laryngeal mechanoreceptors to both static (step indentations) and dynamic (vibratory) forms of mechanical stimulation was undertaken using a servo-controlled mechanical stimulator. In both species two predominant classes of mechanoreceptors were observed (Boushey, Richardson, Widdicombe and Wise, 1974). One class was distinguished by a regular and continuous pattern of activity at a frequency of 10-70 Hz (tonic fibres, sixty-six in cat, thirty-five in rabbit). The other class was silent or (more rarely) irregularly active at a very low frequency (silent fibres, eighty-two in cat, twenty-three in rabbit). The location of the receptive fields was determined by manual probing. Inter-species and regional variations in receptive field location were observed for the two fibre groups. Conduction velocity was measured for twenty-one tonic and seven silent fibres in the rabbit by a pre-triggered averaging technique. The results obtained (tonic: range 10.8-30.0, mean .+-. S.E. of mean 21.4 .+-. 1.2 m/s; silent: 14.8-28.6, 20.4 .+-. 1.8 m/s) were characteristic of group III afferent fibres but were not significantly different for the two classes. Both classes of receptor showed a response at the onset of a step indentation of the region of the mucosa that corresponded to their receptive field. Subsequent to this brief initial response the behaviour of the two classes diverged markedly. Tonic fibres were invariably slowly adapting whereas most (forty-four out of fifty-five in cat; twenty-two out of twenty-three in rabbit) silent fibres were rapidly adapting, at least for smaller indentation amplitudes. Receptors of both classes were readily entrained to discharge at the same frequency as the probe stimulator (1:1 entrainment) when this was made to vibrate upon the receptive area for test periods of 0.5 or 1.0 s. Tuning curves were constructed of the minimum amplitudes required to elicit 1:1 entrainment throughout an entire test period at various frequencies. Individual fibres in the two classes could be entrained at frequencies up to 400 Hz or more at sensitive (e.g. < 100 .mu.m) vibratory amplitudes. However, all fibres were less sensitive at these higher frequencies than at some lower point on the frequency scale. Rapidly adapting, silent fibres had curves which usually exhibited identifiable minima (10-60 Hz), but the curves or these, and other silent fibres, were relatively broadly tuned. Slowly adapting, silent fibres had curves which were particularly flat in the lower range of frequencies. Tonic fibres had curves were also more sensitive at the lower frequencies that approached their spontaneous discharge rate, but could not normally be ''stimulated'' to fire at frquencies less than this. It was concluded that the dynamic sensitivity of fibres from the various locations would ensure a high probability of the movement of a foreign particle into the larynx being signalled at most velocities and on most laryngeal surfaces.