Kawasaki K, Saeki Y, Ohnuki Y
Department of Orthodontics, Tsurumi University School of Dental Medicine, Yokohama, Japan.
Arch Oral Biol. 1997 Jul;42(7):505-12. doi: 10.1016/s0003-9969(97)00038-1.
To study the effects of increased occlusal vertical dimension on these kinetics, the actin-filament sliding velocity on masseter myosins in an in vitro motility assay and the ATPase activity of masseter myosins from normal (control) and bite-opened (5.6 mm increase in the vertical dimension for 1 week) guinea-pigs were measured. In control myosin preparations, the average value (mean +/- SD, n = 5) for the actin-filament sliding velocity at 25 degrees C was 4.0 +/- 0.3 microns/sec. In bite-opened myosin preparations (n = 5), it was 3.4 +/- 0.3 microns/sec, a significant (p < 0.01) decrease. Myosin ATPase activity was also decreased significantly (p < 0.01) from 1.0 +/- 0.1 to 0.7 +/- 0.1 mumol Pi mg per min (mean +/- SD, n = 5) after the bite opening. These results strongly suggest that in guinea-pigs an increase in occlusal vertical dimension for 1 week decreases the turnover rate of actin-myosin interaction in the masseter through changes in the myosin isozyme. These changes may result in a slowing of the rate of detachment of myosin cross-bridges from actin filaments.
为了研究咬合垂直距离增加对这些动力学的影响，我们在体外运动分析中测量了正常（对照）和开咬（垂直距离增加5.6毫米，持续1周）豚鼠咬肌肌球蛋白上肌动蛋白丝的滑动速度，并测定了咬肌肌球蛋白的ATP酶活性。在对照肌球蛋白制剂中，25℃时肌动蛋白丝滑动速度的平均值（均值±标准差，n = 5）为4.0±0.3微米/秒。在开咬的肌球蛋白制剂中（n = 5），该速度为3.4±0.3微米/秒，显著降低（p < 0.01）。咬开后，肌球蛋白ATP酶活性也从1.0±0.1显著降低（p < 0.01）至0.7±0.1微摩尔无机磷/毫克·分钟（均值±标准差，n = 5）。这些结果有力地表明，在豚鼠中，咬合垂直距离增加1周会通过肌球蛋白同工酶的变化降低咬肌中肌动蛋白 - 肌球蛋白相互作用的周转率。这些变化可能导致肌球蛋白横桥从肌动蛋白丝上脱离的速度减慢。
