The presence of granules in atrial cardiomyocytes of all mammalian species, including man, led de Bold et al.[1] to make the crucial observation that intravenous administration of extracts of atrial homogenates induced rapid, massive diuresis and natriuresis in rats. Subsequently, it was shown that not only the atria but also the ventricles are able to synthesize and secrete a peptide hormone (called ANF or ANP) with natriuretic properties. It was therefore ascertained that the heart has a well-established endocrine function, as it is able to syn-thesize and secrete a family of related peptide hormones (gen-erally known as cardiac peptide hormones) with potent diuretic, natriuretic, vascular smooth muscle-relaxing effects and with complex interactions with the hormonal and nervous systems. As cardiac peptide hormones have important fluidvolume regulatory features, it has been postulated that they play a key role in volume homeostasis in normal conditions as well as in several pathophysiological states, in particular con-gestive heart failure 12—8].

Because the key observation of de Bold et al.[1] originated a huge explosion of studies on the pathophysiological effects and on the alleged clinical importance of cardiac peptide hormones, we focused this review specifically on the potential clinical relevance of the assay of these hormones as measured by different methods recently developed. For the reader's convenience, a more comprehensive list of studies concerning all biological effects and/or pathophysiologic implications related to the cardiac peptide hormones can be found in the review articles cited in the references.