Mechanisms of contraction in molluscan muscle

Abstract

The muscles of molluscs show a wide variety of structural types, a variation that is paralleled by the behavior of the muscles. All these muscles have certain features in common; they contain long filaments of two types, but differ in the length and thickness of the thick filaments and in the proportion of the protein, paramyosin, in the muscle. Structural and physiological experiments suggest that the basic contractile mechanism is the same in all molluscan muscles. The muscle-relaxing mechanism, however, may be specialized, particularly in certain smooth muscles which have the very slow relaxation characteristic of "catch" muscles. © 1967 by the American Society of Zoologists.