The Relation of Muscle Biochemistry to Muscle Physiology

Abstract

During the last several years, the major challenge in the field of muscle contraction has been to develop a detailed theory explaining how muscle develops force and produces work. There is now general agreement that the overall mechanism of muscle contraction involves the sliding of the thick myosin filaments past the thin actin filaments, a process driven by the hydrolysis of ATP (29, 31). Most workers also agree that this sliding process is caused by a cyclic interaction of the actin filaments with cross-bridges extending from the myosin filament (28, 29, 31). However, the details of this cyclic interaction remain elusive. The cyclic interaction of the myosin cross-bridges with the actin filaments has been investigated from structural, physiological, and biochemical view­ points. This review discusses how these three viewpoints might be united in a single view of cross-bridge action . Rather than attempt an exhaustive review of the literature, we focus on various biochemical models proposed for the actomyosin ATPase and how they relate to the mechanism of muscle contraction. In addition, a new model of cross-bridge action in vivo is presented, based on a biochemical model that appears to fit best the current biochemical data.