Tarr M, Trank J W, Goertz K K
Circ Res. 1984 Jan;54(1):58-64. doi: 10.1161/01.res.54.1.58.
The effects of stretches and releases on the contractile performance of isolated single frog atrial cells (Rana catesbeiana) were investigated. A stretch or release was imposed on the cell--either during a contraction (test) or before the onset of contraction (control)--and the contractile performance (length, velocity and force) of the test contraction was compared with that of the control contraction to determine whether the stretch or release imposed on the contracting cell altered the contractility of the cell. We found that the velocity of cell (and sarcomere) shortening for the remainder of the test contraction following either a stretch or release was markedly less than that occurring at the same time in the control contraction. This decreased velocity occurred even though the force in the test contraction was less than that in the control contraction and the sarcomere length was longer in the test contraction than in the control contraction. These results indicate that after a stretch or release imposed on the contracting cell, the force-velocity relationship at any given length and time is depressed than had the stretch or release not been imposed on the contracting cell. Thus, stretches and releases applied to the contracting single cardiac cell either produce a long-term depression in the contractility of the cell, or that the contractility at any given time and sarcomere length depends markedly on the history of the contraction.
研究了拉伸和释放对分离的单个青蛙心房细胞（牛蛙）收缩性能的影响。在细胞收缩期间（测试）或收缩开始前（对照）对细胞施加拉伸或释放，将测试收缩的收缩性能（长度、速度和力量）与对照收缩的进行比较，以确定施加于收缩细胞的拉伸或释放是否改变了细胞的收缩性。我们发现，在拉伸或释放后，测试收缩剩余部分的细胞（和肌节）缩短速度明显低于对照收缩同时的缩短速度。即使测试收缩中的力量小于对照收缩中的力量，且测试收缩中的肌节长度比对照收缩中的更长，这种速度降低仍然发生。这些结果表明，在对收缩细胞施加拉伸或释放后，在任何给定长度和时间的力-速度关系都比未对收缩细胞施加拉伸或释放时更低。因此，施加于收缩的单个心肌细胞的拉伸和释放要么会导致细胞收缩性的长期降低，要么在任何给定时间和肌节长度下的收缩性明显取决于收缩的历史。
