Kurebayashi N, Ogawa Y
J Muscle Res Cell Motil. 1985 Apr;6(2):189-95. doi: 10.1007/BF00713060.
For proper interpretation of the results of drug-induced calcium release experiments with skinned fibres, it is necessary to know the direct effects of the drug on the contractile system. We examined the action of quercetin and its various solvents on mechanically skinned skeletal muscle fibre which is deprived of functioning sarcoplasmic reticulum by Triton X-100. Dimethyl sulphoxide (DMSO) at 1%, a solvent for quercetin, decreased reversibly Ca2+ sensitivity for the contractile system of frog skeletal muscle. Alcohol was similar to dimethyl sulphoxide. Polyethylene glycol was used as a solvent for quercetin, because the solvent at 1% was found to be inert to the pCa-tension relationship. Quercetin increased reversibly Ca2+ sensitivity of the contractile system with the unchanged maximum tension, the pCa-tension relationship being less steep. Since quercetin did not change calcium binding to troponin C from rabbit skeletal muscle, the effect may be due to modified molecular interactions which follow calcium binding to troponin C. The drug might also affect the interaction between troponin subunits. Because DMSO did not affect calcium binding to troponin C, either DMSO also modulates the interaction between troponin subunits and/or it modulates molecular interactions after calcium binding which lead to tension development.
为了正确解读用剥除肌膜纤维进行的药物诱导钙释放实验结果，有必要了解药物对收缩系统的直接作用。我们研究了槲皮素及其各种溶剂对经机械剥除肌膜的骨骼肌纤维的作用，该纤维已被 Triton X - 100破坏了肌浆网功能。槲皮素的溶剂1%二甲基亚砜（DMSO）可逆地降低了青蛙骨骼肌收缩系统对Ca2+的敏感性。乙醇与二甲基亚砜类似。聚乙二醇用作槲皮素的溶剂，因为发现1%的该溶剂对pCa - 张力关系呈惰性。槲皮素可逆地增加了收缩系统对Ca2+的敏感性，同时最大张力不变，pCa - 张力关系变平缓。由于槲皮素不改变兔骨骼肌肌钙蛋白C与钙的结合，这种作用可能是由于钙与肌钙蛋白C结合后分子相互作用发生了改变。该药物也可能影响肌钙蛋白亚基之间的相互作用。由于DMSO也不影响钙与肌钙蛋白C的结合，所以DMSO要么也调节肌钙蛋白亚基之间的相互作用，要么调节钙结合后导致张力产生的分子相互作用。
