Rader Erik P, Cederna Paul S, Weinzweig Jeffrey, Panter Kip E, Yu Deborah, Buchman Steven R, Larkin Lisa M, Faulkner John A
Department of Surgery, University of Michigan, Ann Arbor, MI 48109-2200, USA.
Cleft Palate Craniofac J. 2007 Mar;44(2):216-22. doi: 10.1597/06-036.1.
Levator veli palatini muscles from normal palates of adult humans and goats are predominantly slow oxidative (type 1) fibers. However, 85% of levator veli palatini fibers from cleft palates of adult goats are physiologically fast (type 2). This fiber composition difference between cleft and normal palates may have implications in palatal function. For limb muscles, type 2 muscle fibers are more susceptible to lengthening contraction-induced injury than are type 1 fibers. We tested the hypothesis that, compared with single permeabilized levator veli palatini muscle fibers from normal palates of adult goats, those from cleft palates are more susceptible to lengthening contraction-induced injury.
Congenital cleft palates were the result of chemically-induced decreased movement of the fetal head and tongue causing obstruction of palatal closure. Each muscle fiber was maximally activated and lengthened.
Fiber type was determined by contractile properties and gel electrophoresis. Susceptibility to injury was assessed by measuring the decrease in maximum force following the lengthening contraction, expressed as a percentage of the initial force.
Compared with fibers from normal palates that were all type 1 and had force deficits of 23 +/- 1%, fibers from cleft palates were all type 2 and sustained twofold greater deficits, 40 +/- 1% (p = .001).
Levator veli palatini muscles from cleft palates of goats contain predominantly type 2 fibers that are highly susceptible to lengthening contraction-induced injury. This finding may have implications regarding palatal function and the incidence of velopharyngeal incompetence.
成年人类和山羊正常腭部的腭帆提肌主要由慢氧化型（1型）纤维组成。然而，成年山羊腭裂腭帆提肌中85%的纤维在生理上是快肌型（2型）。腭裂和正常腭部之间的这种纤维组成差异可能对腭部功能有影响。对于肢体肌肉，2型肌纤维比1型纤维更容易受到拉长收缩诱导的损伤。我们检验了这样一个假设：与成年山羊正常腭部的单个通透化腭帆提肌纤维相比，腭裂的腭帆提肌纤维更容易受到拉长收缩诱导的损伤。
先天性腭裂是化学诱导胎儿头部和舌头运动减少导致腭部闭合受阻的结果。每根肌纤维都被最大程度激活并拉长。
通过收缩特性和凝胶电泳确定纤维类型。通过测量拉长收缩后最大力量的下降来评估损伤易感性，以初始力量的百分比表示。
与正常腭部全为1型且力量缺失为23±1%的纤维相比，腭裂的纤维全为2型，且力量缺失大两倍，为40±1%（p = 0.001）。
山羊腭裂的腭帆提肌主要含有2型纤维，这些纤维极易受到拉长收缩诱导的损伤。这一发现可能对腭部功能和腭咽闭合不全的发生率有影响。
