Smooth muscle: contraction hypothesis based on the arrangement of actin and myosin filaments in different states of contraction*

Open Access
Publisher Website
Google Scholar
Abstract
Electron microscopical studies were m ade of the changes occurring during contraction of mouse taenia coli. In relaxed fibres actin filaments were found clearly ordered into bundles. W ithin the bundles the filaments were often arranged in rows or in a hexagonal lattice. In the areas between the filament bundles thick filaments were detected. The shortened fibres showed a different appearance. Thick and thin filaments were interm ingled in a random fashion. By com paring these findings with observations m ade on invertebrate smooth muscles, a model for smooth muscle contraction is proposed. According to this hypothesis the contractile apparatus of smooth muscles is composed of small contraction units of interdigitating bundles of thick and thin filaments. They seem to be irregularly shaped and random ly arranged. During the contraction the sets of filaments slide into each other. The result is the intermingling of the thick and thin filaments found in contracted fibres.

This publication has 0 references indexed in Scilit: