Work production and work absorption in muscle strips from vertebrate cardiac and insect flight muscle fibers.
Work production and work absorption in muscle strips from vertebrate cardiac and insect flight muscle fibers.
复制标题
脊椎动物心脏和昆虫飞行肌纤维的肌肉条中的功产生和功吸收。
DOI：
10.1007/978-1-4684-6039-1_52
复制
发表时间：
1998
影响因子：
--
通讯作者：
Mulieri,LA
中科院分区：
文献类型：
--
作者：
Maughan,D;Moore,J;Vigoreaux,J;Barnes,B;Mulieri,LA
伸展激活是所有横纹肌做振荡功的能力的基础，是昆虫飞行和脊椎动物心肌的显著特征。我们研究并比较了果蝇肌、小鼠乳头肌和人心室肌条的皮肤纤维的做功和吸收过程。使用小振幅正弦长度扰动分析，我们区分可归因于其他结构的肌节的crossbridge过程的粘弹性。通过对复杂的刚度数据进行反卷积，确定了Ca 2+活化纤维的做功和做功吸收过程。一个“主动”的工作产生过程（“B”），归因于crossbridge行动，被确定为两个工作吸收过程，一个归因于crossbridge行动（“C”）和其他主要的粘弹性平行被动结构（“A”）。最大Ca 2+激活时（pCa 5，27°C），最大净功率输出（过程A，频带C组合）发生的频率为：人为1.3 ± 0.1 Hz，小鼠为10.9 ± 2.2 Hz，苍蝇为226 ± 9 Hz，与人的静息心率相当（1Hz，37°C）和小鼠（10 Hz，37°C）以及果蝇（200 Hz，22°C）的翅拍频率。过程B每个肌球蛋白头的最大功产生为每个扰动循环7-11 × 10 - 21 J，相当于大约2 kT的能量。过程C的最大功吸收大约是相同的量级。等效性表明，热棘轮型机制在小幅度长度扰动的可能性。我们推测，机械耗能器可能具有生存优势（即，C过程）在肌肉中起作用，如果它们可以被它们运作的系统有害地拉伸。
Stretch activation, which underlies the ability of all striated muscles to do oscillatory work, is a prominent feature of both insect flight and vertebrate cardiac muscle. We have examined and compared work-producing and work-absorbing processes in skinned fibers ofDrosophilaflight muscle, mouse papillary muscle, and human ventricular strips. Using small amplitude sinusoidal length perturbation analysis, we distinguished viscoelastic properties attributable to crossbridge processes from those attributable to other structures of the sarcomere. Work-producing and work-absorbing processes were identified in Ca2+-activated fibers by deconvolving complex stiffness data. An ‘active’ work-producing process (“B”), attributed to crossbridge action, was identified, as were two work-absorbing processes, one attributable to crossbridge action (“C”) and the other primarily to viscoelastic properties of parallel passive structures(“A”). At maximal Ca2+-activation (pCa 5, 27°C), maximum net power output (processesA, Band C combined) occurs at a frequency of: 1.3 ± 0.1 Hz for human, 10.9 ± 2.2 Hz for mouse, and 226 ± 9 Hz for fly, comparable to the resting heart rate of the human (1 Hz, 37°C) and mouse (10 Hz, 37°C) and to the wing beat frequency of the fruit fly (200 Hz, 22°C). Process B maximal work production per myosin head is 7–11 x 10∼21J per perturbation cycle, equivalent to approximately 2 kT of energy. Process C maximal work absorption is about the same magnitude. The equivalence suggests the possibility that a thermal ratchet type mechanism operates during small amplitude length perturbations. We speculate that there may be a survival advantage in having a mechanical energy dissipater (i.e., the C process) at work in muscles if they can be injuriously stretched by the system in which they operate.