COMPARISON OF CROSSBRIDGE DYNAMICS BETWEEN INTACT AND SKINNED MYOCARDIUM FROM FERRET RIGHT VENTRICLES
COMPARISON OF CROSSBRIDGE DYNAMICS BETWEEN INTACT AND SKINNED MYOCARDIUM FROM FERRET RIGHT VENTRICLES
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DOI：
10.1161/01.res.68.3.772
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发表时间：
1991-03-01
影响因子：
20.1
通讯作者：
ZHAO, Y
中科院分区：
文献类型：
--
作者：
SAEKI, Y;KAWAI, M;ZHAO, Y
本研究比较了完整的和皮肤的制剂从雪貂心肌在20摄氏度的crossbridge动力学，以确定是否剥皮引起任何改变的crossbridge响应强加的长度变化。 从右心室分离乳头肌或小梁肌，调整肌肉长度以获得最大抽搐张力（L（max）），并使制备物发生Ba 2+挛缩。 当稳定的张力发展，制备的长度正弦扰动在19个离散的频率，范围从0.13至135 Hz，并在一个小的峰-峰振幅（0.25% L（最大））。 我们确定了三个指数过程中的正弦力响应的长度振荡，这些被标记为过程B，C和D的速度增加的顺序。 一个缓慢的过程，A，通常存在于快速收缩的骨骼肌中，在心肌中非常小或不存在。 过程B是指数延迟，肌肉对施力装置产生振荡功;过程C和D是指数推进，肌肉吸收功。 将制剂化学去皮并在（mM）CaEGTA 6（pCa 4.55）、MgATP 5、丙酸镁1和磷酸盐1的存在下活化，pH 7.0，用丙酸钾将离子强度调节至200 mM。 我们发现，交联动力学没有改变的剥皮程序。 从正弦分析中提取的表观速率常数在Ba 2+挛缩（完整制备）和Ca 2+激活（皮肤制备）中几乎相同，Nyquist图也相似。 由于速率常数与底物（MgATP）的浓度敏感地改变，我们得出结论，在完整的制备过程中的Ba 2+挛缩的基板是足够的供应。 我们的研究证明了从完整和带皮制剂中获得的结果的相容性。
This study compares the crossbridge kinetics of intact and skinned preparations from ferret cardiac muscles at 20-degrees-C to determine whether skinning causes any alteration in the crossbridge response to an imposed length change. A papillary or trabecular muscle was isolated from the right ventricle, the muscle length adjusted to give the maximum twitch tension (L(max)), and the preparation was subjected to Ba2+ contracture. When steady tension developed, the length of the preparation was perturbed sinusoidally in 19 discrete frequencies, ranging from 0.13 to 135 Hz, and at a small peak-to-peak amplitude (0.25% L(max)). We identified three exponential processes in the sinusoidal force-response to the imposed length oscillation, and these were labeled processes B, C, and D in order of increasing speed. A slow process, A, normally present in fast-twitch skeletal muscles, is very small or absent in cardiac muscles. Process B is an exponential delay, and the muscle produces oscillatory work on the forcing apparatus; processes C and D are exponential advances in which the muscle absorbs work. The preparation was chemically skinned and activated in the presence of (mM) CaEGTA 6 (pCa 4.55), MgATP 5, magnesium propionate 1, and phosphate 1, pH 7.0, with ionic strength adjusted to 200 mM with potassium propionate. We found that the crossbridge kinetics were not altered by the skinning procedure. The apparent rate constants extracted from the sinusoidal analysis were nearly identical in Ba2+ contracture (intact preparation) and in Ca2+ activation (skinned preparation), and the Nyquist plots were similar. Because the rate constants changed sensitively with the substrate (MgATP) concentrations, we concluded that the substrate is adequately supplied during Ba2+ contracture in the intact preparation. Our study demonstrates the compatibility of results obtained from an intact and from a skinned preparation.