Godlewska-Hammel Elzbieta, Büschges Ansgar, Gruhn Matthias
Department for Animal Physiology, Biocenter Cologne, Zoological Institute, Zülpicher Strasse 47b, 50674, Cologne, Germany.
J Comp Physiol A Neuroethol Sens Neural Behav Physiol. 2017 Oct;203(10):773-790. doi: 10.1007/s00359-017-1190-8. Epub 2017 Jun 8.
Previous studies have demonstrated that myofibrillar ATPase (mATPase) enzyme activity in muscle fibers determines their contraction properties. We analyzed mATPase activities in muscles of the front, middle and hind legs of the orthopteran stick insect (Carausius morosus) to test the hypothesis that differences in muscle fiber types and distributions reflected differences in their behavioral functions. Our data show that all muscles are composed of at least three fiber types, fast, intermediate and slow, and demonstrate that: (1) in the femoral muscles (extensor and flexor tibiae) of all legs, the number of fast fibers decreases from proximal to distal, with a concomitant increase in the number of slow fibers. (2) The swing phase muscles protractor coxae and levator trochanteris, have smaller percentages of slow fibers compared to the antagonist stance muscles retractor coxae and depressor trochanteris. (3) The percentage of slow fibers in the retractor coxae and depressor trochanteris increases significantly from front to hind legs. These results suggest that fiber-type distribution in leg muscles of insects is not identical across leg muscles but tuned towards the specific function of a given muscle in the locomotor system.
先前的研究表明，肌肉纤维中的肌原纤维ATP酶（mATPase）活性决定了其收缩特性。我们分析了直翅目竹节虫（Carausius morosus）前腿、中腿和后腿肌肉中的mATP酶活性，以检验肌肉纤维类型和分布的差异反映其行为功能差异这一假设。我们的数据表明，所有肌肉至少由三种纤维类型组成，即快肌纤维、中间肌纤维和慢肌纤维，并证明：（1）在所有腿部的股部肌肉（胫节伸肌和屈肌）中，快肌纤维数量从近端到远端逐渐减少，同时慢肌纤维数量相应增加。（2）与拮抗的站立肌肉（髋部内收肌和转子下压肌）相比，摆动期肌肉（髋部前转肌和转子提肌）的慢肌纤维百分比更小。（3）髋部内收肌和转子下压肌中慢肌纤维的百分比从前腿到后腿显著增加。这些结果表明，昆虫腿部肌肉中的纤维类型分布在不同腿部肌肉中并不相同，而是针对运动系统中特定肌肉的特定功能进行了调整。
