Brady A J, Farnsworth S P
Am J Physiol. 1986 Jun;250(6 Pt 2):H932-43. doi: 10.1152/ajpheart.1986.250.6.H932.
Myocytes were prepared from enzymatically digested adult rat hearts and attached to concentric double-barreled suction micropipettes. Myocyte stiffness was calculated as the ratio of the oscillatory tension-to-strain amplitude, where the strain was produced by an applied 5-Hz perturbation. Stiffness, as a function of cell length, was measured in relaxing solution (pCa = 9) as the control solution, 0.5% Triton X-100 detergent, 0.47 M KCl, and 0.6 M KI. Ultrastructure of unattached cells in each solution is illustrated with electron micrographs. The dependence of cell stiffness on cell length was described by an exponential relation with a length constant that increased slightly in detergent, whereas the stiffness at control length appeared to fall. The major fall in absolute stiffness occurred with myosin extraction in KCl. Both the stiffness at control length and the slope of the ln stiffness-to-length relation declined with the disappearance of the A band. A further, but smaller, decline of stiffness occurred with KI extraction of the thin filaments. A highly compliant "ghost" remained after KI extraction but the stiffness-to-length relation was still measurable. The fall in stiffness with myosin extraction is discussed in relation to cytoskeletal filaments (titin, nebulin, and intermediate filaments.
心肌细胞取自成年大鼠经酶消化的心脏，并附着于同心双管吸引微吸管上。心肌细胞硬度通过振荡张力与应变幅度的比值计算得出，其中应变由施加的5赫兹扰动产生。在松弛溶液（pCa = 9）作为对照溶液、0.5% Triton X - 100去污剂、0.47 M KCl和0.6 M KI中，测量硬度作为细胞长度的函数。用电子显微镜照片展示了每种溶液中未附着细胞的超微结构。细胞硬度对细胞长度的依赖性通过指数关系描述，其长度常数在去污剂中略有增加，而对照长度下的硬度似乎下降。绝对硬度的主要下降发生在KCl中肌球蛋白提取时。对照长度下的硬度以及ln硬度与长度关系的斜率均随A带消失而下降。细丝经KI提取后硬度进一步下降，但降幅较小。KI提取后仍保留高度顺应性的“空壳”，但硬度与长度关系仍可测量。结合细胞骨架细丝（肌联蛋白、伴肌动蛋白和中间丝）讨论了肌球蛋白提取导致的硬度下降。
