Smooth muscle mechanics in context

Smooth muscle mechanics and cellular function

An adequate understanding of the mechanical function of smooth muscle must integrate cellular events, extracellular interconnections and interactions, and subcellular and molecular events into a coordinated contraction of the tissue as a whole. At the center of this range of function is the smooth muscle cell, and its study has been approached from several directions. Approached from the tissue level, muscle function reveals behavior that requires a cellular explanation; approaching cellular function from the direction of the biochemical or physical interactions of isolated cellular constituents has provided some of these explanations. Attempts to understand smooth muscle mechanical function at all levels of organization are obviously necessary, and it is ultimately through the integration of all avenues of approach that an adequate picture will emerge. Mechanical studies of smooth muscle tissues inherently provide this kind of integration. This chapter will attempt to treat smooth muscle mechanics thoroughly enough to give the reader insight into both the adequacies and shortcomings of the kinds of mechanical measurements in widespread use in smooth muscle research.

The discussions in this chapter will be confined to vertebrate smooth muscle, mostly that of mammals, even though nonstriated muscles are found elsewhere in the animal kingdom, most notably among the mollusks (Prosser 1967; Ruegg 1971). Although much has been learned from invertebrate smooth muscle, the phylogenetic relationships between vertebrate and invertebrate muscles are unclear, and many aspects of their physiology and biochemistry are quite different.