Relation between steady-state force and intracellular [Ca2+] in intact human myocardium. Index of myofibrillar responsiveness to Ca2+.
Relation between steady-state force and intracellular [Ca2+] in intact human myocardium. Index of myofibrillar responsiveness to Ca2+.
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完整人心肌中稳态力与细胞内 [Ca2] 之间的关系。
DOI：
10.1161/01.cir.82.4.1266
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发表时间：
1990
期刊：
影响因子：
37.8
通讯作者：
Hajjar,RJ
中科院分区：
文献类型：
--
作者：
Gwathmey,JK;Hajjar,RJ
一种新的方法被开发允许测量稳态力和细胞内钙浓度（[Ca2+]i）在破伤风的人室性小梁没有药物干预。我们比较和对比了评估肌丝钙敏感性的三种方法：1)在剥皮纤维制剂中的力-[Ca2+]关系，2)峰值抽搐力-峰值[Ca2+]i关系，以及3)完整肌肉中的稳态力-[Ca2+]i关系。通过在15-20 Hz的刺激频率下，破伤风完整的人小梁，加载aequorin（一种Ca2（+）敏感的生物发光蛋白），可以快速实现稳态收缩激活。在破伤风期间测量稳态力和[Ca2+]i，并通过改变细胞外钙浓度（[Ca2+]o）获得力与[Ca2+]i的关系。从对照和肌病心脏获得的力-[Ca2+]i关系拟合到Hill方程：%Force = [Ca2+]inh/([Ca2+]inh50% + [Ca2+]inh)，其中nh是Hill系数，[Ca2+]50%是50%激活所需的[Ca2+]。正常肌和肌病肌的破伤风曲线Hill系数分别为5.21 +/- 0.20 （n = 6）和5.61 +/- 0.60 (n = 10)， [Ca2+]50%分别为0.56 +/- 0.05 microM （n = 6）和0.54 +/- 0.09 microM （n = 10）。我们还利用来自同一肌肉的等距抽搐构建了峰值力-峰值[Ca2+]i关系。与稳态力-[Ca2+]i曲线相比，这些曲线向更高的[Ca2+]i曲线偏移。Ryanodine （1 microM）增加了Ca2+和力瞬变的时间过程，使峰值力-峰值[Ca2+]i关系向左移动，但不影响稳态力-[Ca2+]i关系。暴露于10毫米的咖啡因使稳态力-[Ca2+]i关系向左移动，而暴露于3微米的异丙肾上腺素使这种关系向右移动。皮纤维制备的实验与来自同一心脏的完整肌肉实验同时进行。对照和肌病组织中皂苷皮小梁的力- pca （-log[Ca2+]）关系是重叠的。Ryanodine（1微米）对剥皮纤维的力- pca关系没有影响。强直后抽搐诱发最大张力，比强直时大。这种增强作用在肌浆网抑制剂瑞诺定的存在下被消除。我们提出稳态力-[Ca2+]i关系的变化与肌丝对Ca2+敏感性的变化相关，而峰值力-峰值[Ca2+]i关系的变化代表了抽搐瞬态的时间变化。（摘要删节为400字）
A novel approach was developed allowing the measurement of steady-state force and intracellular calcium concentration ([Ca2+]i) in tetanized human ventricular trabeculae carneae without pharmacological intervention. We compared and contrasted three methods of assessing calcium sensitivity of the myofilaments: 1) force-[Ca2+] relations in skinned fiber preparations, 2) peak twitch force-peak [Ca2+]i relations, and 3) steady-state force-[Ca2+]i relations in intact muscles. Steady-state contractile activation was achieved rapidly by tetanizing intact human trabeculae, loaded with aequorin, a Ca2(+)-sensitive bioluminescent protein, at a stimulation frequency of 15-20 Hz. Steady-state force and [Ca2+]i were measured during tetani, and the force versus [Ca2+]i relation was obtained by varying the extracellular calcium concentration ([Ca2+]o). Force-[Ca2+]i relations obtained from control and myopathic hearts were fitted to the Hill equation: %Force = [Ca2+]inh/([Ca2+]inh50% + [Ca2+]inh), where nh is the Hill coefficient, and [Ca2+]50% is the [Ca2+] required for 50% activation. The curves of tetani had Hill coefficients of 5.21 +/- 0.20 (n = 6) and 5.61 +/- 0.60 (n = 10) and [Ca2+]50% of 0.56 +/- 0.05 microM (n = 6) and 0.54 +/- 0.09 microM (n = 10) in control and myopathic muscles, respectively. We also constructed peak force-peak [Ca2+]i relations using isometric twitches from the same muscles. These curves were shifted toward higher [Ca2+]i compared with the steady-state force-[Ca2+]i curve derived from tetani. Ryanodine (1 microM), which increased the time course of the Ca2+ and force transients, shifted the peak force-peak [Ca2+]i relation to the left, without affecting the steady-state force-[Ca2+]i relation. Exposure to 10 mM caffeine shifted the steady-state force-[Ca2+]i relation to the left, whereas exposure to 3 microM isoproterenol shifted this relation to the right. Experiments using skinned fiber preparations were performed in parallel with experiments on intact muscles from the same hearts. The force-pCa (-log[Ca2+]) relations in saponin-skinned trabeculae from control and myopathic tissue were superimposable. Ryanodine (1 microM) had no effect on the force-pCa relation in skinned fibers. Maximal tension was evoked by the posttetanic twitch, which was larger than the tetanus. This potentiation was abolished in the presence of ryanodine, a sarcoplasmic reticulum inhibitor. We propose that the changes in the steady-state force-[Ca2+]i relations are correlated with alterations in the sensitivity of the myofilaments to Ca2+, whereas changes in the peak force-peak [Ca2+]i relations represent temporal changes in the twitch transient.(ABSTRACT TRUNCATED AT 400 WORDS)
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肌酸激酶在化学剥皮大鼠心肌力量发展中的作用
DOI：
--
发表时间：
1987
期刊：
The Journal of General Physiology
影响因子：
--
作者：
R. Ventura;H. Mekhfi;G. Vassort
通讯作者：
G. Vassort
肥大兔心脏的钙激活肌肉：机械和相关的生化变化
影响因子：
20.1
作者：
D. Maughan;E. Low;R. Litten;J. Brayden;Norman Axpert
通讯作者：
Norman Axpert
影响因子：
3.4
作者：
CANNELL, MB;ALLEN, DG
通讯作者：
ALLEN, DG
DOI：
10.1113/jphysiol.1981.sp013580
发表时间：
1981-02
期刊：
The Journal of Physiology
影响因子：
--
作者：
F. Julian;R. Moss
通讯作者：
F. Julian;R. Moss
强直刺激雪貂乳头肌和整个心脏引起的最大 Ca2+ 激活力：完整心肌稳定收缩激活的机制和特征
影响因子：
20.1
作者：
E. Marbán;H. Kusuoka;D. T. Yue;M. Weisfeldt;W. Wier
通讯作者：
W. Wier