Molluscan catch muscle: Regulation and mechanics in living and skinned anterior byssus retractor muscle ofMytilus edulis
Immediate stiffness and static elastic modulus were estimated in skinned and living molluscan smooth muscle during active contraction and catch state. The stiffness to tension ratio was found to be greater in catch than in active contraction. In skinned preparations, a catch like state could be reproduced in a Ca2+ free solution (pCa>8) which was mechanically not different from catch in living muscle. Addition of cAMP or the catalytic subunit of the cAMP dependent protein kinase type II caused a rapid relaxation of this catch like state. The results are discussed in terms of a dual intracellular regulatory mechanism of catch and active contraction.
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