舒张期张力对雪貂心肌单收缩中Ca2+瞬变和张力时程的影响。
Effect of developed tension on the time courses of Ca2+ transients and tension in twitch contraction in ferret myocardium.
作者信息
Komukai K, Kurihara S
机构信息
Department of Physiology, Jikei University School of Medicine, Tokyo, Japan.
出版信息
Cardiovasc Res. 1996 Aug;32(2):384-90. doi: 10.1016/0008-6363(96)00084-3.
OBJECTIVES
The aim of the study is to test the hypothesis that tension-dependent change in the affinity of cardiac troponin-C influences the time courses of Ca2+ transients and tension in twitch contraction.
METHODS
The Ca(2+)-sensitive photoprotein, aequorin, was microinjected into superficial cells of ferret papillary muscles and the Ca2+ transients and tension were simultaneously measured. The peak of developed tension was altered by changing the extracellular Ca2+ concentration, initial muscle length, and the application of 2,3-butanedione monoxime.
RESULTS
In each maneuver, the decay time of Ca2+ transients was prolonged and the tension relaxation time was shortened when the peak of developed tension was decreased. In contrast, when the peak of developed tension was increased, the decay time of Ca2+ transients was shortened and the tension relaxation time was prolonged. The decay time of Ca2+ transients measured with different maneuvers was negatively correlated with the peak tension and the tension relaxation time was positively correlated with the tension peak.
CONCLUSIONS
The changes in the decay time of Ca2+ transients and the tension relaxation time indicate that developed tension modulates the affinity of troponin-C for Ca2+ in normal twitch contraction.
目的
本研究旨在验证如下假说，即心肌肌钙蛋白C亲和力的张力依赖性变化会影响抽搐收缩中Ca2+瞬变和张力的时间进程。
方法
将Ca(2+)敏感光蛋白水母发光蛋白显微注射到雪貂乳头肌的表层细胞中，同时测量Ca2+瞬变和张力。通过改变细胞外Ca2+浓度、初始肌肉长度以及应用2,3-丁二酮单肟来改变最大张力峰值。
结果
在每次操作中，当最大张力峰值降低时，Ca2+瞬变的衰减时间延长，张力松弛时间缩短。相反，当最大张力峰值增加时，Ca2+瞬变的衰减时间缩短，张力松弛时间延长。通过不同操作测得的Ca2+瞬变衰减时间与峰值张力呈负相关，张力松弛时间与张力峰值呈正相关。
结论
Ca2+瞬变衰减时间和张力松弛时间的变化表明，在正常抽搐收缩中，最大张力调节肌钙蛋白C对Ca2+的亲和力。
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