THE HEART AS AN ENDOCRINE ORGAN

In addition to the renin-angiotensin-aldosterone system and the antidi uretic hormone (ADH), the cardiac natriuretic peptide hormones ANP and BNP are important regulators of fluid and electrolyte households. The y are thought to play an important part in the acute regulation of the body fluid balance. As preload and afterload of the heart represent t he important determinants of hormone secretion from the heart, we stud ied the influence of artificial cardiac pacemaker stimulation or prelo ad increase. Here, a very sensitive reaction of the ''endocrine heart' ' could be found. An incongruous rise in ANP and BNP plasma concentrat ion points to at least partly independent mechanisms govering the rele ase of both hormones depending on the trigger of ANP and BNP release.