Uncontrolled sarcomere shortening increases intracellular Ca2+ transient in rat cardiac trabeculae
Uncontrolled sarcomere shortening increases intracellular Ca2+ transient in rat cardiac trabeculae
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DOI：
10.1152/ajpheart.1997.272.4.h1892
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发表时间：
1997-04-01
影响因子：
4.8
通讯作者：
deTombe, PP
中科院分区：
文献类型：
--
作者：
Janssen, PML;deTombe, PP
分离的心肌制剂存在末端顺应性受损的问题，在肌肉总长度保持不变的收缩过程中，这种顺应性允许中央肌节大幅缩短。抽搐时肌节不受控制的缩短对心肌细胞内钙瞬变的影响尚不清楚。因此，在本研究中，我们开发了一种迭代的激光衍射反馈系统，该系统能够准确控制中央节段肌节长度，并同时测量离体心小梁中离子导入注入的Fura-2荧光。我们比较了在常规抽动和中央肌节长度(SL)通过反馈控制保持恒定的抽动中记录的Fura-2荧光信号。(‘’SL夹子‘’抽动)。我们发现，不受控制的肌节缩短与钙瞬变峰值的显著增加有关(P=0.005)，并且这种增加的幅度与中央节段肌节缩短的程度直接相关(r(2)=0.92P<；0.01)。而钙瞬变的时程不受收缩方式的影响(P=0.64)。这些发现对于解释心肌钙离子转运的研究具有重要意义，在这些研究中，肌节不受控制地缩短发生在抽动过程中。
Isolated cardiac muscle preparations suffer from damaged-end compliance that allows for substantial shortening of central sarcomeres during contractions in which the overall length of muscle is kept constant. The impact of uncontrolled sarcomere shortening during a twitch on the intracellular calcium transient in myocardium is unknown. Accordingly, in the present study we developed an iterative laser-diffraction feedback system that allowed for the accurate control of central-segment sarcomere length and simultaneous measurement of iontophoretically injected fura 2 fluorescence in isolated cardiac trabeculae. We compared fura 2 fluorescence signals recorded during regular twitches with twitches in which central sarcomere length (SL) was held constant by feedback control. (''SL clamp'' twitches). We found that uncontrolled sarcomere shortening was associated with a significant (P = 0.005) increase in the peak of the calcium transient and that the amount of this increase was directly correlated to the extent of central-segment sarcomere shortening (r(2) = 0.92; P < 0.01). The time course of the calcium transient, however, was unaffected by the mode of contraction (P = 0.64). These findings have important implications for the interpretation of studies of myocardial calcium handling in which uncontrolled sarcomere shortening takes place during the twitch.