[Coronary-active bovine heart proteins induce relaxation in the rabbit aorta]

Seven cardioactive polypeptides have been identified in the precardiac and auricular regions of the bovine heart. Those polypeptides were studied for their action on the function of isolated preparations of the vessel. It has been found that compounds isolated from the precardiac region induce different (20-55%) relaxation of smooth muscles in a strip of the aorta of rabbit. The possibility of formation of endogenic cardioactive compounds in model experiments imitating processing is studied. The data obtained permit assuming and alternatively explaining existence of multiple forms of the mentioned compounds as a result of partial proteolytic splitting of larger molecules.