TEMPORAL (CIRCADIAN) AND FUNCTIONAL-RELATIONSHIP BETWEEN ATRIAL NATRIURETIC PEPTIDES AND BLOOD-PRESSURE

Long-acting natriuretic peptide, vessel dilator, and atrial natriureti c 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, respe ctively, 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 obtai ned 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 me n were studied twice) to compare circulating concentrations of atrial natriuretic peptides with naturally occurring changes in blood pressur e. Overall, vessel dilator, long-acting natriuretic peptide, and ANF e ach had significant (p < 0.001) circadian rhythms, with peak concentra tions late during sleep (at 04:00 h) being nearly twice their concentr ations in the afternoon and evening. This high-amplitude circadian cha nge allowed for the refinement of normal limits for ANF peptides by co mputing 3-hourly tolerance intervals (chronodesms) against which to co mpare time-specified single samples for normality, Systolic, diastolic , and mean arterial blood pressure also had significant circadian rhyt hms (p < 0.001) with peaks and troughs that were exactly opposite thos e of the ANF peptides, In addition to this inverse temporal relationsh ip, there was a significant inverse correlation between absolute value s for blood pressure and each ANF peptide (p < 0.001), implying a func tional 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 mainte nance of blood pressure and modulation of its circadian rhythm.