[Atrial natriuretic peptide, renin-aldosterone system and arterial pressure. Analysis by circadian rhythm measurement]

Abstract

Six voluntary, clinically healthy, non-smoking, male subjects were studied to estimate and eventually quantify the role of the circadian rhythm of atrial natriuretic peptide and of the renin-aldosterone system in the conditioning and genesis of the circadian rhythm of arterial blood pressure. After a week of standard life condition, during the span of a day, with the subjects in constant supine position, venous blood samples were drawn every four hours, while arterial blood pressure was measured every two hours. Plasma levels of atrial natriuretic peptide, renin activity, and aldosterone were determined by radioimmunoassay. The time-related values of each variable were analysed by the "cosinor" method. The cosinor analysis shows a statistically significant (p less than 0.05) circadian rhythm for all variables studied. These data suggest an inverse relationship between the circadian rhythm of atrial natriuretic peptide and that of arterial blood pressure, with a chronological sequence in the atrial natriuretic peptide-plasma renin activity-aldosterone axis.