Stretch induced tension rise in a molluscan smooth muscle skinned by freeze drying

The anterior byssus retractor muscle (ABRM) of Mytilus edulis was skinned by freeze drying. Tension transients in response to quick length steps were recorded during isometric contraction induced in ATP salt solution containing 2 x 10 super(-6) M Ca super(2+). These transients consisted of four phases similar to those described by Huxley (1974) in skeletal muscle. Under certain conditions (stretch amplitude not larger than 0.6% L sub(0)), and in particular in the presence of cyclic AMP, the authors observed a delayed tension rise following a quick stretch (stretch activation) which appears to be similar to the stretch activation of insect flight muscle (Jewell and Rueegg 1966).