Shall Mary S, Lanzino Desiree J, Van Cleave Susan, Goldberg Stephen J
Department of Physical Therapy, Box 980224, Virginia Commonwealth University, Richmond, VA 23298-0224, USA.
J Vestib Res. 2005;15(5-6):253-62.
Children with hypoactive semicircular canals commonly have delayed motor development. We studied ferrets whose vestibular labyrinths were removed at postnatal day 10 (P10) to evaluate 1) development of motor behavior, 2) soleus contractile characteristics, 3) muscle fiber diameter, and 4) the expression of myosin heavy chain (MHC) isoforms. At P30 labyrinthectomized (LAB) ferrets exhibited a significant delay in motor development. At P120, the LAB ferrets continued to have significantly more difficulty with dynamic balance than the SHAM ferrets. At P30, the muscle fibers were about the same diameter as those in the sham operated ferrets (SHAM) at the same age but significantly more developmental MHC isoforms were expressed in the LAB soleus muscle. At P120, both the LAB soleus and medial gastrocnemius expressed significantly more type IIX MHC. The P120 LAB soleus muscle was significantly weaker and the muscle fibers were significantly smaller. These results support the hypothesis that vestibular receptors are important to the development of upright posture and balance activities, and influence muscle fiber development and MHC expression in postural muscles.
半规管活动减退的儿童通常存在运动发育迟缓的情况。我们研究了在出生后第10天（P10）切除前庭迷路的雪貂，以评估：1）运动行为的发育；2）比目鱼肌的收缩特性；3）肌纤维直径；4）肌球蛋白重链（MHC）亚型的表达。在P30时，迷路切除（LAB）的雪貂表现出明显的运动发育延迟。在P120时，LAB雪貂在动态平衡方面仍比假手术（SHAM）雪貂有明显更多的困难。在P30时，肌纤维直径与同年龄假手术（SHAM）雪貂的肌纤维直径大致相同，但LAB比目鱼肌中表达的发育型MHC亚型明显更多。在P120时，LAB比目鱼肌和腓肠肌内侧均表达了明显更多的IIX型MHC。P120时LAB比目鱼肌明显较弱，肌纤维明显较小。这些结果支持了以下假设：前庭感受器对直立姿势和平衡活动的发育很重要，并影响姿势肌的肌纤维发育和MHC表达。
