Introduction

Abstract

The function of the contractile or regulatory proteins depends critically on their chemical environment. Consequently, there are a variety of experiments under way that are designed to measure the exact composition of muscle cytosol. Ionic H, Ca, Mg and MgATP, for example, are particularly important quantities inasmuch as these ions, as mediators and substrate, profoundly affect the rate and magnitude of force developed by muscle fibers. In vivo measurements are important, especially in trying to distinguish pathological and normal states and in seeking the causes for particular myopathies.