Fiber types of the intrinsic whisker muscle and whisking behavior
Fiber types of the intrinsic whisker muscle and whisking behavior
复制标题
DOI：
10.1523/jneurosci.5151-03.2004
复制
发表时间：
2004-03-31
影响因子：
5.3
通讯作者：
Brecht, M
中科院分区：
文献类型：
--
作者：
Jin, TE;Witzemann, V;Brecht, M
一些啮齿类动物表现出有节奏的振动伸展和收缩，被称为轻拂，这是哺乳动物中最快的动作之一。为了更好地理解剃须的肌肉基础，我们比较了(1)两个剃须物种（小鼠、大鼠）和一个不剃须物种（豚鼠）的剃须运动，(2)剃须和不剃须物种的剃须固有肌肉的肌纤维组成，(3)剃须固有肌肉和选定骨骼肌的肌纤维组成。通过高速摄像，我们发现小鼠、大鼠和豚鼠可以产生快速、大振幅的胡须运动。豚鼠没有表现出快速的、严格有节奏的胡须运动，它们胡须运动的平均速度比小鼠和大鼠要低得多。肌球蛋白重链异构体的mRNA表达分析、肌纤维atp酶染色和抗体标记表明，在这三个物种中，内在须肌肉主要由2B型肌纤维组成。小鼠固有须肌由2B型（大于等于90%）和2D型纤维组成。在大鼠中，我们观察到，除了2B/2D型纤维外，还有接近10%的慢速1型纤维，在豚鼠中，我们观察到接近3%的慢速1型纤维和20%的2A型纤维。2B型纤维具有高水平的厌氧糖酵解酶，提供快速的ATP来源和高的最大收缩速度，但比其他类型的肌肉纤维更不耐疲劳。高百分比的2B型纤维将内在须肌肉组织与骨骼肌区分开来，可能是为了快速扫描感官环境而进化的。
Some rodent species show rhythmic bouts of vibrissal protractions and retractions, referred to as whisking, that are among the fastest movements performed by mammals. To better understand the muscular basis of whisking, we compared (1) whisker movements of two whisking species (mouse, rat) and a non-whisking species (guinea pig), (2) the muscle fiber composition of intrinsic whisker muscles of whisking and a non-whisking species, and ( 3) the muscle fiber composition of intrinsic whisker muscles and of selected skeletal muscles. Using high-speed videography, we found that mice, rats, and guinea pigs can generate fast and large-amplitude whisker movements. Guinea pigs do not show bouts of fast, strictly rhythmic whisker movements, and the average speed of their whisker movements is much lower than in mice and rats. Analysis of mRNA expression of myosin heavy chain isoforms, myofibrillar ATPase staining, and antibody labeling indicate that in all three species intrinsic whisker muscles are composed predominantly of type 2B muscle fibers. Intrinsic whisker muscles of mice consisted of type 2B (greater than or equal to90%) and type 2D fibers. In rats we observed, in addition to type 2B/2D fibers, similar to10% of slow type 1 fibers, and in guinea pigs we observed similar to3% of slow type 1 fibers and 20% of type 2A fibers. Type 2B fibers have high levels of anaerobic glycolytic enzymes providing a rapid source of ATP and high maximum velocity of contraction but are less fatigue resistant than other muscle fiber types. The high percentage of type 2B fibers distinguishes the intrinsic whisker musculature from skeletal muscles and may have evolved for fast scanning of the sensory environment.