A one-dimensional viscoelastic model of cat heart muscle studied by small length perturbations during isometric contraction.
A one-dimensional viscoelastic model of cat heart muscle studied by small length perturbations during isometric contraction.
复制标题
通过等长收缩过程中的小长度扰动研究猫心肌的一维粘弹性模型。
作者：
L. Loeffler;K. Sagawa
为了建立一个心肌模型，我们研究了猫乳头肌在固定变力状态下的准等长收缩。静息肌肉的性质通过使用小于1.2%Lmax的步进拉伸来确定，初始长度从85%Lmax到100%Lmax。被动力响应表明了被动分支的模型（图1）。所有五个参数都很小，在肌肉长度低于95%的Lmax，但在较长的长度显着增加。用正弦长度变化（幅度小于Lmax的0.15%，频率0.1- 35.0Hz）研究收缩肌肉的特性。主动刚度（总刚度减去被动刚度）的频率响应表明了主动分支的模型（图1）。我们通过记录随主动力（FA）线性变化的长度和时间Ks的各种组合下的频率响应，确定了弹性元件（K，Ks）和粘性元件（C）对长度和时间的依赖性。K和C表现出的时间过程，使FA高达0.6tmax，并保持其值，直到1.4tmax。然后K下降到零，而C在下降到零之前表现出二次上升。K是依赖于长度的Lmax的95%，然后开始下降，但C变化成比例的肌肉长度。
To develop a model of heart muscle, we studied cat papillary muscle contracting in a quasi-isometric condition under a fixed inotropic state. The properties of resting muscle were determined by using a step stretch of less than 1.2% of Lmax for initial lengths from 85 to 100% Lmax. The passive force response suggested the model of the passive branch (Fig. 1). All five parameters were small at muscle lengths below 95% of Lmax but increased markedly at longer lengths. The properties of contracting muscle were studied with a sinusoidal length change (amplitude less than 0.15% of Lmax, frequency 0.1-35.0 Hz). The frequency response of active (total minus passive) stiffness suggested the model of the active branch (Fig. 1). We determined the dependency of the elastic elements (K, Ks) and the viscous element (C) on length and time by recording the frequency response at various combinations of length and time Ks varied linearly with active force (FA). K and C exhibited time courses that paralleled FA up to 0.6tmax, and they maintained their values until 1.4tmax. K then fell toward zero, whereas C exhibited a secondary rise before it fell toward zero. K was dependent of length up to 95% of Lmax and then began to decline, but C varied in proportion to muscle length.