More than bricks and mortar: comments on protein and amino acid metabolism in the heart.

Few cardiologists have considered that constituents of the heart muscle cells are in a continuous state of flux. The proteins of sarcomeres, mitochondria, membranes, the cytosol, and even ribosomes and the cell nucleus, are continuously degraded and remade. Schoenheimer's concept of the "dynamic state of body constituents," has received relatively little attention in the world of cardiovascular research, at least not until recently. We propose that the term nutrition of the heart extends well beyond the supply of energy-providing substrates and includes the supply of amino acids, micronutrients, and regulators of protein synthesis and degradation. This short article is written to make the reader think in broad concepts.