Characteristics of Actin-Myosin Interaction in Different Regions of Rat Heart

The ventricles and atria of the mammalian heart have differencesin structure and function at different levels of organization. However,the current data on mechanical function of the heart chambers atdifferent levels are contradictory and demand a detailed study.We compared mechanical characteristics of actin-myosin interactionby an in vitro motility assay and structural characteristics ofcontractile and regulatory proteins by one-dimensional denaturating polyacrylamidegel electrophoresis (SDS-PAGE) in atria, septum, right, and leftventricles. The sliding velocity of the reconstituted thin filamentsover atrial myosin was significantly higher compared to other myocardiumregions. No differences were observed in sliding velocity of atrial, septal,and ventricular native thin filaments over the myosin from the samemyocardium region of the same rats. At the same time, the slidingvelocity of the atrial native thin filament over porcine myosinwas lower than that of the ventricular and septal native thin filament.