The Heart

In an editorial published almost 25 years ago, Braunwald et al¹(perhaps tongue in cheek) referred to the heart as an endocrine organ. They referred to the ability of the myocardium and its nerve supply to produce and store catecholamines for later release. Over the years the concept of an endocrine function of the heart lay dormant, but during the last two or three years a rapidly developing series of studies from a number of laboratories have demonstrated that a factor is produced in the atrium that may be responsible for excretion of sodium and water. To the cardiologist this concept will be easily acceptable since, from a teleologic point of view, it is logical to accept the idea that if there is one locus in the body that can sense and adjust for a circulatory overload, it must be located in the low-pressure area of the circulation and,