Titin-based modulation of active tension and interfilament lattice spacing in skinned rat cardiac muscle
Titin-based modulation of active tension and interfilament lattice spacing in skinned rat cardiac muscle
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DOI：
10.1007/s00424-004-1354-6
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发表时间：
2005-02-01
影响因子：
4.5
通讯作者：
Granzier, H
中科院分区：
文献类型：
--
作者：
Fukuda, N;Wu, YM;Granzier, H
通过测量肌节长度（SL）依赖性的Ca 2+敏感性变化和进行小角X射线衍射研究，研究了肌联蛋白为基础的被动张力对大鼠心室肌小梁主动张力和肌丝间晶格间距的Ca 2+敏感性的影响。为了改变被动张力，在20 ℃下用低浓度（0.31 μ g/ml）胰蛋白酶短时间（13分钟）处理制备物，导致肌联蛋白I带区域降解约40%，对A带肌联蛋白的影响最小。我们发现，胰蛋白酶对肌联蛋白基被动张力的影响在拉伸后立即比在稳定状态下拉伸后30分钟（即，胰蛋白酶对粘度的影响大于对被动心肌弹性的影响）。在SL 2.25妈妈，但不是在SL 1.9妈妈，胰蛋白酶治疗的Ca 2+的敏感性下降，导致显着衰减的SL依赖性增加Ca 2+的敏感性。钙敏感性的SL依赖性变化与基于肌联蛋白的被动张力显著相关。小角X射线衍射实验表明，胰蛋白酶处理后，晶格间距扩大，特别是在SL 2.25妈妈，提供了一个逆线性关系的晶格间距和Ca 2+的敏感性。这些结果支持这样的观点，肌联蛋白为基础的被动张力促进肌动球蛋白的相互作用，其机制包括丝间晶格间距调制。
The effect of titin-based passive tension on Ca2+ sensitivity of active tension and interfilament lattice spacing was studied in skinned rat ventricular trabeculae by measuring the sarcomere length (SL)dependent change in Ca2+ sensitivity and performing small angle X-ray diffraction studies. To vary passive tension, preparations were treated with trypsin at a low concentration (0.31 mug/ml) for a short period (13 min) at 20degreesC, that resulted in similar to40% degradation of the I-band region of titin, with a minimal effect on A-band titin. We found that the effect of trypsin on titin-based passive tension was significantly more pronounced immediately after stretch than at steady state, 30 min after stretch (i.e., trypsin has a greater effect on viscosity than on elasticity of passive cardiac muscle). Ca2+ sensitivity was decreased by trypsin treatment at SL 2.25 mum, but not at SL 1.9 mum, resulting in marked attenuation of the SL-dependent increase in Ca2+ sensitivity. The SL-dependent change in Ca2+ sensitivity was significantly correlated with titin-based passive tension. Small-angle X-ray diffraction experiments revealed that the lattice spacing expands after trypsin treatment, especially at SL 2.25 mum, providing an inverse linear relationship between the lattice spacing and Ca2+ sensitivity. These results support the view that titin-based passive tension promotes actomyosin interaction and that the mechanism includes interfilament lattice spacing modulation.