Mechanism of Catch Force: Tethering of Thick and Thin Filaments by Twitchin
Figure 1
Contractile responses of intact anterior byssus retractor muscle of Mytilus edulis. Muscles were bathed in artificial seawater (ASW) and then treated as shown. (a) Phasic contraction. Muscle was activated with acetylcholine (50 M) and at peak force serotonin (10 M) was added. (b) Activation, catch, and release of catch in intact muscle. Muscle was activated with acetylcholine (50 M) for 1.5 minutes which was washed out with ASW for 1.5 minutes. The condition of high-force maintenance is catch. Catch force was rapidly released upon addition of 10 M serotonin. Lower panel (orange) shows the time course of high-energy phosphate usage during activation and catch [8]. Lower panels (blue) show the time course of the accompanying changes in intracellular Ca++ during phasic and catch contractions based on the work of Ishii et al. [3].
