TRANSITION IN SENSITIVITY OF SPINDLE RECEPTORS THAT OCCURS WHEN MUSCLE IS STRETCHED MORE THAN A FRACTION OF A MILLIMETER
TRANSITION IN SENSITIVITY OF SPINDLE RECEPTORS THAT OCCURS WHEN MUSCLE IS STRETCHED MORE THAN A FRACTION OF A MILLIMETER
复制标题
DOI：
10.1152/jn.1975.38.3.673
复制
发表时间：
1975-01-01
影响因子：
2.5
通讯作者：
HOUK, JC
中科院分区：
文献类型：
--
作者：
HASAN, Z;HOUK, JC
我们研究了34个去感受器对缓慢施加(0.01-1 mm/S)小(0.02-0.2 mm)和中(0.2-1 mm)幅度的斜坡伸展的反应。在麻醉猫背根细丝记录到初级和次级终末的传入放电。1.大多数末端对中等幅度斜坡的反应表现为斜率(不连续)的突变，具有高度的重复性。在恒定拉伸(对于不同受体在50-400微米的范围内)比恒定放电率下更接近于发生间断。它们在次要结尾的情况下就不那么明显了。2.当牵张程度超过50-200微米的过渡幅度时，敏感度发生变化。这些变化是通过构建基于对一系列坡道的响应的曲线图来研究的，这些坡道是彼此的比例版本。这些曲线图表明，在拉伸和适应过程中，敏感度都有所降低；初级末端的敏感度降低比次级末端更为明显。3.肌肉长度的变化对反应有很大的影响。当最后一次变化是增加几毫米时，不连续变得更加明显，动态反应的外观发生了其他变化，特别是在初级结尾的情况下。这些变化可能会持续几分钟，但通过一次中等幅度的测试就可以取消。4.改变肌长时高敏感度的重置、不连续、敏感度的转变、非线性适应和先前长度改变的影响似乎是相关的现象。它们都可以用这样一个假设来解释，即梭内肌肉纤维的极区具有类似摩擦的性质，这类似于已经描述的针对整个肌肉的性质。提出了一个反映这些特征的简单的非线性模型。5.对初级终末放电变化的充分刺激是肌肉长度的微小变化，相对独立于其速度。动力响应主要是由对长度本身变化的敏感性引起的，这是一种非线性特性。
We studied the responses of 34 deefferented spindle receptors to slowly applied ramp stretches (0.01-1 mm/s) of small (0.02-0.2 mm) and intermediate (0.2-1 mm) amplitudes. The afferent discharge from primary and secondary endings was recorded from filaments of dorsal root in anesthetized cats. 1. Responses of most endings to ramps of intermediate amplitude showed abrupt changes in slope (discontinuities) which were highly repeatable. Discontinuities occurred more nearly at constant stretch (in the range 50-400 mum for different receptors) than at constant discharge rate. They were less pronounced in the case of secondary endings. 2. Changes in sensitivity occurred when the degree of stretch exceeded a transitional amplitude which ranged from 50 to 200 mum. These changes were studied by constructing plots based on a family of responses to a family of ramps which were scaled versions of each other. The plots indicated that reductions in sensitivity occurred both during stretch and during adaptation; the reductions were more marked for primary than for secondary endings. 3. Responses were modified considerably by preceding changes in muscle length. When the last change was an increase of a few millimeters, discontinuities became more pronounced and other changes in the appearance of the dynamic response occurred, particularly in the case of primary endings. These changes could last for several minutes, but were abolished by a single test stretch of intermediate amplitude. 4. The resetting of high sensitivity that occurs when muscle length is changed, the discontinuities, the transitions in sensitivity, nonlinear adaptation, and the effects of previous length change appeared to be related phenomena. They can all be accounted for by the hypothesis that polar zones of intrafusal muscle fibers possess a frictionlike property, one analogous to that which has been described for whole muscle. A simple nonlinear model which shows these features is presented. 5. The adequate stimulus for a change in primary ending discharge is a small change in muscle length, relatively independently of its velocity. The dynamic response arises mainly from a changing sensitivity to length itself, which is a nonlinear property.