Figure 3: Sarcomere length dependence of the rate constant of force redevelopment ( ). (a) Slow time-based recordings of sarcomere length and force obtained using an IonOptix SarLen system during a slack restretch maneuver during submaximal Ca2+ activation. (b) Sarcomere length-dependence of for rat slow-twitch skeletal muscle fibers, rat cardiac myocytes, and pig cardiac myocytes. Although pig cardiac myocyte was much slower at all sarcomere lengths compared to rat cardiac myocytes, both pig and rat cardiac cell preparations showed that increased at short sarcomere lengths despite reductions in force implicating that sarcomere length overrides the Ca2+ activation dependence of .