title: Effect of an increase in occlusal vertical dimension on the rate of cyclic actin-myosin interaction in guinea-pig masseter muscle.
abstract: 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.
authors.affiliation: Department of Orthodontics, Tsurumi University School of Dental Medicine, Yokohama, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Kawasaki
authors.forename: Y
authors.initials: Y
authors.lastname: Saeki
authors.forename: Y
authors.initials: Y
authors.lastname: Ohnuki
mesh_terms: D000199:Actins / Q000737:chemistry* / Q000378:metabolism; D000251:Adenosine Triphosphatases / Q000032:analysis / Q000378:metabolism; D000818:Animals; D004347:Drug Interactions; D006168:Guinea Pigs; D008297:Male; D008310:Malocclusion / Q000209:etiology / Q000378:metabolism; D008406:Masseter Muscle / Q000737:chemistry* / Q000378:metabolism; D009218:Myosins / Q000737:chemistry* / Q000378:metabolism; D009967:Orthodontic Appliances; D014716:Vertical Dimension
chemical_list: D000199:Actins; D000251:Adenosine Triphosphatases; D009218:Myosins