CIRCADIAN RELATIONSHIPS BETWEEN CIRCULATING ATRIAL NATRIURETIC PEPTIDES AND SERUM SODIUM AND CHLORIDE IN HEALTHY HUMANS

Long-acting natriuretic peptide (LANP), vessel dilator (VSDL), and atr ial natriuretic factor (ANF) consisting of amino acids 1-30, 31-67, an d 99-126 of the 126 amino acid ANF prohormone, respectively, circulate in humans and have potent natriuretic properties, To determine whethe r 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 hea lthy humans. LANP, VSDL, ANF, and Cl had significant (p < 0.001) circa dian rhythms with peak concentrations at 04.00 h, The circadian rhythm of serum Na was exactly opposite, Sodium correlated negatively with L ANP (p = 0.021) and ANF (p = 0.007), while Cl correlated positively wi th LANP (p = 0.003) and VS DL (p = 0.001). These data suggest that the atrial peptides may be important for the maintenance of serum Na and CI within their normal ranges and in the modulation of their daily cir cadian rhythms.