[Characteristics of cardiac growth and energy metabolism in the development of the clawed toad].

The relative content of the actomyosin complex proteins increases with respect to the total heart protein during the heart growth in Xenopus laevis. The intensity of the heart sections respiration was shown to depend on the heart weight. Constants were determined in an equation describing this dependence. The decrease in the intensity of the heart sections respiration is determined mainly by the decrease of the mitochondrial protein content.