Cross‐bridge behaviour in skinned smooth muscle of the guinea‐pig taenia coli at altered ionic strength.
Cross‐bridge behaviour in skinned smooth muscle of the guinea‐pig taenia coli at altered ionic strength.
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改变离子强度时豚鼠带皮平滑肌的跨桥行为。
DOI：
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发表时间：
1988
期刊：
影响因子：
--
通讯作者：
P. Hellstrand
中科院分区：
文献类型：
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作者：
H. Arheden;A. Arner;P. Hellstrand
1.研究了不同水平（25 - 300 mM）的离子强度对化学去皮豚鼠结肠带绦虫纤维的机械性能和ATP水解速率的影响。2.与150 mM离子强度相比，25 mM离子强度下钙激活后的张力发展（pCa 4.8）和去除钙后的松弛（pCa 9）较慢。在肌球蛋白轻链硫代磷酸化激活的纤维中，通过暴露于ATP-γ-S，张力发展迅速且与离子强度无关。3.根据快速释放法确定的力-速度关系获得最大缩短速度（Vmax）。ATP水解速率（JATP）通过测量从磷酸烯醇丙酮酸（PEP）释放的丙酮酸来确定。为了在ImM的Mg-ATP浓度下获得最大Vmax和JATP，需要ATP再生系统。在硫代磷酸化纤维中，2 mM-磷酸肌酸（PCr）或3.2 mM-PEP分别足以达到最大Vmax和JATP。在钙激活纤维中，最大Vmax需要5 mM-PCr。4.硫代磷酸化纤维的等距力表现出双相依赖于离子强度，最大值为90 mM。Vmax在50和200 mM离子强度之间基本不变。在25 mM离子强度下，等长力和Vmax分别降低约15%和25%。在250 mM离子强度下，等长力和Vmax分别降低了47%和33%。5. Vmax随[Mg-ATP]降低而降低。在[Mg-ATP]小于0.1 mM时，35和150 mM离子强度之间的Vmax没有差异。在所有[Mg-ATP]条件下，250 mM离子强度Vmax均低于150 mM。6.在35、150和250 mM离子强度下，硫代磷酸化纤维收缩期间的JATP分别为0.62、0.98和0.93 mumol g-1 min-1。能量张力成本（JATP/力）随离子强度增加。7.在25，150和250 mM离子强度的放松，收缩和僵硬状态下的力响应快速拉伸进行了研究。在松弛状态下的刚度随着拉伸的速度而增加，并且离子强度越低，刚度越高。在收缩和僵硬状态下，刚度也受到离子强度的影响，但在收缩状态下的相对影响很小。（400字处截断摘要）
1. The effects of varied levels (25‐300 mM) of ionic strength on mechanical properties and ATP hydrolysis rate of chemically skinned guinea‐pig taenia coli fibres were investigated. 2. The tension development following activation by calcium (pCa 4.8), and relaxation following removal of calcium (pCa 9), were slower in 25 mM compared to 150 mM ionic strength. In fibres activated by thiophosphorylation of myosin light chains, by exposure to ATP‐gamma‐S, the tension development was rapid and independent of ionic strength. 3. The maximal shortening velocity (Vmax) was obtained from force‐velocity relations determined by the quick‐release method. The rate of ATP hydrolysis (JATP) was determined by measurement of pyruvate released from phosphoenolpyruvate (PEP). In order to obtain maximal Vmax and JATP at a Mg‐ATP concentration of 1 mM, an ATP regenerating system was required. In thiophosphorylated fibres 2 mM‐phosphocreatine (PCr) or 3.2 mM‐PEP were adequate for maximal Vmax and JATP respectively. In calcium‐activated fibres 5 mM‐PCr was required for maximal Vmax. 4. The isometric force of thiophosphorylated fibres showed a biphasic dependence on ionic strength with a maximum at 90 mM. Vmax was essentially unchanged between 50 and 200 mM ionic strength. At 25 mM ionic strength, isometric force and Vmax were decreased by, respectively, about 15 and 25%. At 250 mM ionic strength, isometric force and Vmax were decreased by, respectively, 47 and 33%. 5. Vmax decreased with decreasing [Mg‐ATP]. At [Mg‐ATP] less than 0.1 mM there was no difference in Vmax between 35 and 150 mM ionic strength. At 250 mM ionic strength Vmax was lower than that at 150 mM at all [Mg‐ATP]. 6. JATP during contraction in thiophosphorylated fibres at 35, 150 and 250 mM ionic strength was respectively, 0.62, 0.98 and 0.93 mumol g‐1 min‐1. The energetic tension cost (JATP/force) increased with ionic strength. 7. The force response to a quick stretch was investigated in the relaxed, contracted and rigor states at 25, 150 and 250 mM ionic strength. Stiffness in the relaxed state increased with speed of stretch and was higher the lower the ionic strength. In the contracted and rigor states, stiffness was also affected by ionic strength, but the relative effect in the contracted state was small.(ABSTRACT TRUNCATED AT 400 WORDS)
原肌球蛋白在平滑肌收缩中的作用：原肌球蛋白与肌动蛋白结合对肌球蛋白 ATP 酶的肌动蛋白激活的影响。
影响因子：
2.9
作者：
Miyata,H;Chacko,S
通讯作者：
Chacko,S