title: Effects of unilateral jaw clenching on cerebral/systemic circulation and related autonomic nerve activity.
abstract: Jaw clenching (clenching) is the result of an isometric contraction of jaw closing muscles. Because of the location of working muscles and afferent information during tooth contact, the effect of clenching on the cerebral and systemic circulation might differ from that of isometric limb exercise. This study aimed to investigate the characteristic changes in cerebral and systemic circulation during jaw clenching by comparing those during handgrip exercise. Subjects were 17 right-handed men. Bilateral middle cerebral arterial blood flow velocity (MCAV), electromyography (EMG) of contracting muscles, heart rate (HR) and blood pressure (BP) were measured during unilateral handgrip exercise and clenching tasks. Autonomic nerve activity was evaluated by analyzing fluctuations in HR and BP. MCAV was significantly increased during the task with significantly higher values on the non-working than working side irrespective of unilateral handgrip or unilateral jaw clenching. Changes in HR during jaw clenching were lower than those during handgrip exercise, and changes in vaso-motor sympathetic nerve activity during left jaw clenching were lower than those during left handgrip exercise. The present results indicate that, compared with handgrip exercise, unilateral jaw clenching promotes bilateral activation of MCAV with smaller effects on cardiac output and sympathetic nervous system activity.
authors.affiliation: Department of General Dentistry & Emergency, School of Stomatology, Fourth Military Medical University, Xi'an, China.
authors.forename: Min
authors.initials: M
authors.lastname: Zhang
authors.forename: Yoko
authors.initials: Y
authors.lastname: Hasegawa
authors.forename: Joe
authors.initials: J
authors.lastname: Sakagami
authors.forename: Takahiro
authors.initials: T
authors.lastname: Ono
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Hori
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Maeda
authors.forename: Yong-Jin
authors.initials: YJ
authors.lastname: Chen
mesh_terms: D000328:Adult; D019540:Area Under Curve; D017776:Autonomic Pathways / Q000502:physiology*; D001783:Blood Flow Velocity / Q000502:physiology; D001794:Blood Pressure; D002560:Cerebrovascular Circulation / Q000502:physiology*; D004562:Electrocardiography; D004576:Electromyography; D007839:Functional Laterality / Q000502:physiology*; D018737:Hand Strength / Q000502:physiology; D006339:Heart Rate; D006801:Humans; D007568:Jaw / Q000502:physiology*; D008297:Male; D008406:Masseter Muscle / Q000502:physiology; D009119:Muscle Contraction / Q000502:physiology*; D017585:Ultrasonography, Doppler, Transcranial / Q000379:methods; D055815:Young Adult