ANF and the renin-angiotensin system in the regulation of sodium balance: longitudinal studies in experimental heart failure.

Over the last three decades the role of the renin-aldosterone axis for the renal conservation of sodium has become well established. In the last several years information has accumulated to indicate that ANF is an important complementary hormonal system involved in the elimination of sodium surfeit. Evidence has been presented to suggest that ANF and the renin-aldosterone axis function in an integrated manner for the regulation of sodium balance, with their primary actions exerted in the postprandial and postabsorptive phases, respectively. It is interesting that this hormonal integration continues to be operational during the compensated stage of experimental heart failure but at the expense of a higher level of activity of the ANF system. The significance of ANF as a compensatory mechanism in chronic heart failure remains to be fully elucidated, although the available longitudinal data in experimental animal models suggest that the role of ANF in the maintenance of sodium balance should be most apparent during the early and mild stages of heart failure, before a marked reduction in cardiac performance leads to an excessive activation of the renin-aldosterone axis that in turn can effectively override the natriuretic actions of ANF.