Regulation of renal tubular sodium transport by cardiac natriuretic peptides: two decades of research.

This review presents the current state of our knowledge regarding the regulation of renal tubular sodium transport by natriuretic peptides, with special emphasis on recent findings in this field. Natriuretic peptides constitute a complex system involved in the regulation of sodium balance and blood pressure. The natriuretic peptide family consists of atrial peptides, such as atrial natriuretic factor (ANF, ANP(99-126)), long-acting natriuretic peptide (ANP(1-30)), vessel dilator (ANP(31-67)) and kaliuretic peptide (ANP(79-98)), as well as brain or B-type natriuretic peptide (BNP), C-type natriuretic peptide (CNP) and urodilatin. Natriuretic peptides act on target cells through A-type and B-type receptors and stimulate cyclic GMP synthesis. ANF stimulates natriuresis mainly by inhibiting sodium reabsorption in the inner medullary collecting duct. The effect results from coordinate inhibition of apical sodium channels and basolateral Na+, K+-ATPase. Additional effects on sodium transport occur in more proximal nephron segments and on glomerular filtration when hormone concentration is elevated. BNP and urodilatin share the same mechanism of action. CNP synthetized in several nephron segments acts through specific B-type natriuretic peptide receptors, which are also expressed in renal tubule, but have a different distribution than A-type receptors. ANP(1-30), ANP(31-67) and ANP(79-98) decrease Na+, K+-ATPase activity in tubular cells through a prostaglandin E2-dependent mechanism.