Myosin Light Chain Composition in Non-Failing Donor and End-Stage Failing Human Ventricular Myocardium

In the heart changes occur in the composition and phosphorylation status of different contractile proteins during development and under pathological conditions1. Such changes may have important consequences for myocardial pump function. In rat myocardium changes in myosin heavy chain (MHC) composition during development and cardiac disease are correlated with changes in myocardial ATPase activity2, 3 and in Ca2+-responsiveness of force4. However, species differences in myocardial contractile protein composition make it difficult to extrapolate these findings to the human heart. Indeed, in several studies it has been proposed that the concepts derived from studies in rodents are not applicable to large mammals5, 6.