The changes in viscosity of an unstriated muscle (Mytilus edulis) during and after stimulation with alternating, interrupted and uninterrupted direct currents
The changes in viscosity of an unstriated muscle (Mytilus edulis) during and after stimulation with alternating, interrupted and uninterrupted direct currents
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无横纹肌（贻贝）在交流、间断和不间断直流电刺激期间和之后的粘度变化
DOI：
10.1113/jphysiol.1937.sp003455
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发表时间：
1937
期刊：
影响因子：
--
通讯作者：
F. R. Winton
中科院分区：
文献类型：
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作者：
F. R. Winton
适当的刺激甚至可以增加粘性，产生融合反应所需的最低刺激频率将相应地降低;因此，在下一个刺激出现之前，肌肉将有时间从一个刺激的不良影响中恢复过来，疲劳不会发展。在贻贝的前回缩器中，直流电刺激增加了粘度，而间断或交流刺激降低了粘度，粘度的变化大大超过了刺激的持续时间[Winton，1934];因此，这个肌肉被选择来研究粘度的变化，凭借这种粘度的变化，强直理论在普通肌肉中可能是成立的。鉴于平滑肌对化学刺激的敏感性，不可能所有强直性收缩的例子都是由于不连续刺激引起的;先前[1930]描述的存在于离体阴茎牵开器中的”恢复力”，以及在贻贝的离体阴茎牵开器中也起作用的“恢复力”（图5），显然是不同的事情。紧张性强直的理论特别适用于那些过去被认为是”捕捉机制”的情况，在这些情况下，神经活动，可能是牵张反射的性质，显然涉及。因为，据我们所知，神经活动是不连续的，普通肌肉如何产生对不连续刺激的紧张性反应的问题就成为一个重要的问题，在以前的通信中讨论了与普通肌肉连接的术语粘度的确切含义[Winton，1930]。牵开器阴茎抵抗拉伸的粘弹性力被证明能够由三分量力学模型表示，该模型由纯弹性、粘弹性和纯粘性元件组成，在一个小的恢复力的影响下，在没有足够大的外部拉伸力来克服它的情况下，引起肌肉缓慢但最终完全缩短。拉伸曲线表明，为狗的阴茎牵开器设计的三重模型充分地代表了贻贝牵开器的机械特性，尽管不是那么令人满意，但在大多数这些肌肉中，曲线的直线部分较短。这两种肌肉的共同点是，它们由平行的纵向排列的无条纹纤维组成，具有相对较少的外来组织，并且它们的大小和形状大致相同，但贻贝牵开器中的单个纤维比狗阴茎牵开器中的纤维长得多。法与其他普通肌肉制备一样，技术上的微小差异可能会在肌肉反应中产生令人惊讶的大变化;下面描述的实验结果是用
CHANGES IN VISCOSITY OF UNSTRIATED MUSCLE 493 suitable stimuli may even increase the viscosity, the least frequency of stimulation needed to produce a fused response would be correspondingly lower; consequently the muscle would have time to recover from the ill effects of one stimulus before the next appeared, and fatigue would not develop. It happens that in the anterior retractor of Mytilus a direct current stimulus increases the viscosity and an interrupted or alternating current stimulus decreases the viscosity, the changes in viscosity greatly outlasting the duration of the stimulus [Winton, 1934]; this muscle has, therefore, been chosen for studying the changes of viscosity in virtue of which a tetanus theory of tonus may be tenable in plain muscle. In view of the sensitivity of plain muscle to chemical stimulation, it is unlikely that all examples of tonic contraction are due to discontinuous stimulation; the" restoring force" previously described [1930] as present in the isolated retractor penis, and also operative in the isolated retractor of Mytilus (Fig. 5 below), is clearly a different affair. The tetanus theory of tonus is particularly applicable to those instances which used to be ascribed to a" catch mechanism", in which nervous activity, possibly of the nature of a stretch reflex, is apparently involved. Since, as far as we know, nervous activity is discontinuous, the problem of how plain muscle yields a tonic response to discontinuous stimulation becomes an important one.The exact meaning of the term viscosity in connexion with plain muscle was discussed in a previous communication [Winton, 1930]. The viscous-elastic forces with which a retractor penis resists stretch were shown to be capable of representation by a triple component mechanical model, consisting of pure elastic, viscous-elastic, and pure viscous elements, under the influence of a small restoring force which induced slow but ultimately full shortening of the muscle in the absence of an external stretching force large enough to overcome it. Stretch curves indicate that the triple model designed for the dog's retractor penis represents adequately, though not quite so satisfactorily, the mechanical properties of the Mytitlus retractor, the straight part of the curve being shorter in most of these muscles. The two muscles have in common that they consist of parallel longitudinally arranged unstriated fibres, with relatively little adventitious tissue, and that they are of about the same size and shape, but the individual fibres in the Mytilus retractor are very much longer than those in the dog's retractor penis. Technique. As with other plain muscle preparations, small differences in technique may produce surprisingly large changes in the reactions of the muscle; the experimental results described below were obtained with