Circadian relationships between circulating atrial natriuretic peptides and serum sodium and chloride in healthy humans.

Long-acting natriuretic peptide (LANP), vessel dilator (VSDL), and atrial natriuretic factor (ANF) consisting of amino acids 1-30, 31-67, and 99-126 of the 126 amino acid ANF prohormone, respectively, circulate in humans and have potent natriuretic properties. To determine whether these peptides have a direct relationship to serum Na and/or Cl, we examined 21 24-hour profiles of these peptides and Na and Cl in 14 healthy humans. LANP, VSDL, ANF, and Cl had significant (p < 0.001) circadian rhythms with peak concentrations at 04.00 h. The circadian rhythm of serum Na was exactly opposite. Sodium correlated negatively with LANP (p = 0.021) and ANF (p = 0.007), while Cl correlated positively with LANP (p = 0.003) and VSDL (p = 0.001). These data suggest that the atrial peptides may be important for the maintenance of serum Na and Cl within their normal ranges and in the modulation of their daily circadian rhythms.