Short communication. Sarcomere length changes during fish swimming.

The interaction between actin and myosin represents the fundamental force-producing mechanism in all skeletal muscles. Interaction between analogous proteins also occurs within cells, resulting in movement of subcellular organelles. Although considerable detail is known about the muscle sarcomere length-tension relationship and how isometric force potential is a function of myofilament overlap (Gordon et al. 1966), there are no direct measurements of myofilament movement during locomotion. We have taken advantage of the transparent morphology of the glass catfish (Kryptopterus bicirri) to investigate noninvasively sarcomere length changes which occur during free swimming. NASA Edited