The American Journal of Physiology - Heart and Circulatory Physiology publishes original investigations on the physiology of the heart, blood vessels, and lymphatics, including experimental and theoretical studies of cardiovascular function at all levels of organization ranging from the intact animal to the cellular, subcellular, and molecular levels. It embraces new descriptions of these functions and of their control systems, as well as their bases in biochemistry, biophysics, genetics, and cell biology. Preference is given to research that provides significant new insights into the mechanisms that determine the performance of the normal and abnormal heart and circulation.