Effects of a mechanical loading on the actomyosin kinetics and the fiber-pherotypes of masticatory muscles.

机械负荷对肌动球蛋白动力学和咀嚼肌纤维表型的影响。

基本信息

批准号：
07457443
负责人：
SAEKI Yasutake
金额：
$ 4.67万
依托单位：
Tsurumi University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1997
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07457443/
关键词：
guinea pig bite-opening in vitro motility assay ATPase activity myosin heavy chain myosin light chain tropomyosin masseter muscle ラットアクチン滑り速度咀嚼筋ミオシンアイソフォーム電気泳動

项目摘要

To study the effects of increased occlusal vertical dimension on (1) the actomyosin kinetics and (2) the fiber-phenotypes of masticatory muscles, we analyzed the sliding velocity of actin filaments on myosins (by an in vitro motility assay), the myosin ATPase activity and the contractile protein compositions in masseter muscles obtained from normal (control) and bite-opened (5.7 mm increase in the vertical dimension for 1 week) guinea pigs.1. Effects of bite-opening on the actomyosin kinetics.In control myosin preparations, the actin-filament sliding velocity at 25ﾟC was 4.0(]SY.+-。[)0.3mum/s (mean(]SY.+-。[)SD, n=5). In bite-opened myosin preparations (n=5), it was 3.4(]SY.+-。[)0.3mum/s, a significant (rho<0.01) decrease. Myosin ATPase activity was also decreased significantly (rho<0.01) from 1.0(]SY.+-。[)0.1 to 0.7(]SY.+-。[)0.1 mumol Pi/mg/min (mean(]SY.+-。[)SD,n=5) after the bite-opening treatment. These results suggest that the 1-week bite-opening treatment decreases the turnover ra … More te of actin-myosin interaction in the masseter.2. Effects of bite-opening on the fiber-phenotypes.Compositions of myosin heavy chain (MHC), myosin light chain (MLC) and tropomyosin were investigated by gel electrophoresis in conjunction with densitometric analysis. Masseter muscle contained two fast-type MHC isoforms, MHC IIa and IId (or IIx). Averaged densitometric data (n=4) indicated no significant (rho>0.05) change in MHC composition between the two groups. Although the MLC consisted of three components, LC1f, LC2f and LC3f, a significant (rho<0.01) increase in the relative content of LC1f at the expense of that of LC3f was observed after the bite-opening treatment. Although the tropomyosin consisted of two components, TM-alpha and TM-beta, a significant (rho<0.05) increase in the relative content of TM-beta as well as a significant (rho<0.05) decrease in that of TM-alpha were observed in association with the bite-opening treatment.These results suggest that in guinea pigs the 1-week bite-opening treatment changes the actomyosin kinetics as well as the compositions of MLC and tropomyosin to meet altered functional demands. Less

为了研究咬合垂直尺寸增加对 (1) 肌动球蛋白动力学和 (2) 咀嚼肌纤维表型的影响，我们分析了肌动蛋白丝在肌球蛋白上的滑动速度（通过体外运动测定），即肌球蛋白 ATP 酶正常（对照）和咬开（1周垂直尺寸增加5.7毫米）几内亚咬肌的活性和收缩蛋白组成1. 咬开对肌动球蛋白动力学的影响。在对照肌球蛋白制剂中，25℃时肌动蛋白丝滑动速度为 4.0(]SY.+-.[)0.3mum/s (平均值(]SY. +-.[)SD，n=5)。 3.4(]SY.+-.[)0.3mum/s，肌球蛋白ATP酶活性显着降低(rho<0.01)，从1.0(]SY.+-.[)0.1显着降低至0.7。 (]SY.+-.[)0.1 mumol Pi/mg/min (平均值(]SY.+-.[)SD,n=5) 咬合后这些结果表明，为期 1 周的咬合治疗降低了咬肌中肌动蛋白-肌球蛋白相互作用的周转率。2. 咬合对纤维表型的影响。肌球蛋白重链 (MHC) 的组成)、肌球蛋白轻链 (MLC) 和原肌球蛋白通过凝胶电泳结合光密度分析进行研究，其中包含两种快速型 MHC。平均光密度数据 (n=4) 表明两组之间的 MHC 组成没有显着变化 (rho>0.05)，尽管 MLC 由 LC1f、LC2f 和 LC3f 三个成分组成。在咬开处理后，观察到 LC1f 的相对含量显着增加（rho<0.01），而 LC3f 的相对含量却有所增加。尽管原肌球蛋白由TM-α和TM-β两种成分组成，但TM-β相对含量显着（rho<0.05）增加以及TM-α相对含量显着（rho<0.05）减少与咬开治疗相关的观察结果。这些结果表明，在豚鼠中，为期 1 周的咬开治疗改变了肌动球蛋白动力学以及成分MLC 和原肌球蛋白以满足改变的功能需求。