Search

Long-acting natriuretic peptide (LANP), vessel dilator (VSDL), and atrial natriuretic factor (ANF) consisting of amino acids (aa) 1 to 30, 31 to 67, and 99 to 126, respectively, of the 126-aa ANF prohormone circulate in humans. Among the biologic properties of these peptides is the ability of ANF to decrease intracellular calcium concentrations. To determine if atrial natriuretic peptides are directly related to serum calcium and/or phosphate in healthy normocalcemic humans, we examined 21 24-hour profiles of VSDL, LANP, ANF, and serum calcium and phosphate in 14 healthy humans. VSDL, LANP, and ANF each had significant (P < .001) circadian rhythms, with peak concentrations late during sleep (at 4:00 AM) being nearly twice the concentrations in the afternoon and evening. Serum calcium and phosphate also had significant circadian rhythms (P < .001) with troughs nearly opposite to those of the atrial natriuretic peptides, suggesting that atrial peptides may be important in the modulation of the circadian rhythms of calcium and phosphate. The nearly identical circadian rhythms of the atrial natriuretic peptides and of parathyroid hormone (PTH) reported by others, along with evidence that PTH may increase atrial peptide release, suggest that some of the effects attributed to PTH may be mediated by atrial natriuretic peptides.

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.

Vessel dilator consisting of amino acids (a.a.) 31-67 and atrial natriuretic factor (ANF) composed of a.a. 99-126 of the 126 a.a. ANF prohormone circulate in humans and have potent vasodilatory properties. To determine whether these atrial natriuretic peptides are directly related to blood pressure in healthy normotensive humans, we recently had the unique opportunity to examine the circadian rhythms of vessel dilator, ANF, and blood pressure in seven individuals in 1988 and again in 1993. The changes in mean arterial pressure and systolic and diastolic blood pressure in these individuals during this 5-year hiatus allows comparison in the same individual, if circulating concentrations of atrial natriuretic peptides directly correlate with naturally occurring changes in blood pressure. In both 1988 and in 1993 vessel dilator and ANF each had significant (p < 0.001) circadian rhythms with their peak concentrations at 4:00 AM being nearly twice their concentrations at 4:00 PM. Mean arterial pressure, systolic blood pressure, and diastolic blood pressure also had significant circadian rhythms with peaks and troughs that were exactly opposite to those of ANF and vessel dilator. A significant inverse correlation between 24-hour averages of mean arterial blood pressure and 24-hour averages of vessel dilator (p = 0.05) and ANF (p = 0.02) was also found. These data suggest that vessel dilator and ANF are important for the maintenance of blood pressure within the normotensive range.

Long-acting natriuretic peptide, vessel dilator, and atrial natriuretic factor consisting of amino acids (a.a.) 1 to 30, 31 to 67, and 99 to 126 of the 126-a.a. atrial natriuretic factor (ANF) prohormone, respectively, circulate in humans and have potent vasodilatory properties. To determine if these atrial natriuretic peptides are directly related to blood pressure in clinically healthy normotensive humans, we obtained 24-h profiles of vessel dilator, long-acting natriuretic peptide, ANF, and blood pressure in 10 men in 1988 and 11 men in 1993 (seven men were studied twice) to compare circulating concentrations of atrial natriuretic peptides with naturally occurring changes in blood pressure. Overall, vessel dilator, long-acting natriuretic peptide, and ANF each had significant (p<0.001) circadian rhythms, with peak concentrations late during sleep (at 04:00 h) being nearly twice their concentrations in the afternoon and evening. This high-amplitude circadian change allowed for the refinement of normal limits for ANF peptides by computing 3-hourly tolerance intervals (chronodesms) against which to compare time-specified single samples for normality. Systolic, diastolic, and mean arterial blood pressure also had significant circadian rhythms (p<0.001) with peaks and troughs that were exactly opposite those of the ANF peptides. In addition to this inverse temporal relationship, there was a significant inverse correlation between absolute values for blood pressure and each ANF peptide (p<0.001), implying a functional relationship. These data suggest that in addition to other well-established neurochemical factors, the ANF peptides (vessel dilator, long-acting natriuretic peptide, and ANF) are important for the maintenance of blood pressure and modulation of its circadian rhythm.