THE AURICULAR NATRIURETIC FACTOR (ANP) - PAST AND FUTURE-RESEARCH

Since the hypotensive and natriuretic properties of crude cardiac extr acts were first demonstrated in 1981 in the rat, the effector molecule has been isolated, purified and synthesized. The hormonal factor is p roduced by atrial myocytes in mammals and stored as a prohormone. Secr etion mainly results from a volemic stress inducing an atrial stretch. Secretion includes a maturation step. A peptide of 28 amino-acids (AN P) is then released into the bloodstream. ANP has a half-life of a few minutes. ANP binds to specific receptors expressed at the target cell surface. B-receptors mediate the biological actions of ANP by an incr ease in cCMP while C-receptors are involved in clearance of the peptid e. The kidney as well as the cardiovascular and endocrine systems are the main target sites for ANP. The renal effects of ANP are expressed by an enhanced diuresis and natriuresis which may result from an incre ased glomerular filtration rate and/or a reduced tubular reabsorption of salt and water. Renal hemodynamics may also be modified due to a re nal specific vasodilator effect of ANP. The reduction of systemic bloo d pressure may result from changes in cardiac output and/or in periphe ral vascular resistance. Several neurohumoral interactions of ANP also contribute to sustain the cardiovascular and renal effects described above. In view of these properties, ANP is of particular interest in o rder to understand the homeostasis of salt and water under physiologic al as well as or physiopathological conditions. In this regard, therap eutic prospects are intensively investigated. Finally, evolutionnary p erspectives are actually considered from studies in lower vertebrates.