Changes in thick filament length in limulus striated muscle

Abstract

Here we describe the change in thick filament length in striated muscle of Limulus, the horseshoe crab. Long thick filaments (4.0 µm) are isolated from living, unstimulated Limulus striated muscle while those isolated from either electrically or K+-stimulated fibers are significantly shorter (3.1 µm) (P > 0.001). Filaments isolated from muscle glycerinated at long sarcomere lengths are long (4.4 µm) while those isolated from muscle glycerinated at short sarcomere lengths are short (2.9 µm) and the difference is significant (P > 0.001). Thin filaments are 2.4 µm in length. The shortening of thick filaments is related to the wide range of sarcomere lengths exhibited by Limulus telson striated muscle. © 1977, Rockefeller University Press., All rights reserved.