The creatine kinase system and cardiomyopathy

Changes in the creatine kinase system, cellular energetics, regulation of respiration and alterations in parameters of contractility in experimental animals (myopathic hamsters), and in patients with dilated cardiomyopathy were studied. 31 P-NMR methods were used to show that cardiomyopathic hearts are characterized by decreased work index, lower tissue ATP, phosphocreatine, and total creatine contents and diminished creatine kinase activity and energy fluxes. In isolated mitochondria, only the creatine kinase activity was decreased. Both in cardiomyopathic hamsters and human hearts a share of mitochondrial creatine kinase in the total tissue enzyme activity was decreased from 33% to 18% and that of BB elevated from 5% in control to 20%, at an unchanged relative level of MM