Atrial natriuretic peptide: a hormone with implications for clinical practice.

The heart functions as an endocrine organ, releasing atrial natriuretic peptide (ANP), a hormone, in response to sodium and fluid overload. Specifically, ANP is released by cardiac myocytes in response to atrial distension. As a hormone, ANP has far-reaching multiorgan effects. The body systems affected include the cardiovascular, renal, neural, gastrointestinal, and endocrine systems. However, the main effects of this hormone are on the renin-angiotensin-aldosterone system. ANP acts to oppose this system by causing vasorelaxation, blocking the secretion and sodium-retaining effects of aldosterone, and inhibiting renal renin secretion. ANP has many potential implications for clinical practice in both short-term and long-term care of patients with fluid and electrolyte balance. Clinicians may use methods to enhance or block endogenous ANP secretion based on assessment of clinical disorder, cause, status of homeostatic mechanisms, and implications for treatment. In addition, ANP may soon be administered pharmacologically, as well as monitored hematologically, in patients with fluid volume overload. In this article we describe the physiologic effects of ANP and address specific implications for clinical practice.