Concepedia

Abstract

The anterior byssal retractor muscle (ABRM) is a molluscan smooth muscle that when appropriately stimulated can be made to perform two distinct types of contraction: (1) a phasic contraction that relaxes upon cessation of stimulation, and (2) a contraction known as “catch” that continues long after stimulation has ended. The latter type is marked by an energy output much smaller than that during phasic contraction (Nauss and Davies, 1969; Baguet and Gillis, 1968); during catch there are neither signs of active state as measured by quick-release experiments (Jewell, 1959; Johnson and Twarog, 1960) nor electrical activity as measured by intracellular or extracellular experiments (Twarog, 1967a).