FURTHER STUDIES ON HUMAN CARDIAC AND VOLUNTARY MUSCLE

Abstract

A number of studies have shown that the creatine concentration of cardiac and voluntary muscle is decreased in certain pathologic conditions. This work has been summarized in an earlier paper from this laboratory.¹The fundamental cause of the decrease in concentration of creatine in heart failure and other pathologic conditions has not been elucidated. However, certain facts are known that have an important bearing on this subject. Creatine is present in muscle largely in the form of phosphocreatine.²That the exact amount present in this form cannot be determined by analysis is due to its rapid breakdown during manipulation of the sample. The best analyses suggest that about 75 to 80 per cent of the creatine present in voluntary muscle is in the form of phosphocreatine while in cardiac muscle the relative amount present in this form is much lower. Creatine can be readily washed out of cardiac