12 November 2008
Diurnal change of plasma atrial natriuretic peptide (ANP) concentration was investigated in 12 patients with hypertension due to chronic renal failure (CRF) and in 12 patients with essential hypertension (EH) of comparable degree. Blood pressure (BP) monitoring was performed at 15-min intervals, while peripheral blood samples were obtained at 4-hour intervals starting from 8.00 h. The mean 24-hour plasma levels ( ± SEM) of ANP were 24.3 ± 1.8 pmol/l in EH and 23.4 ± 1.2 pmol/l in CRF. In EH, plasma ANP concentration was highest at 4.00 h (33.5 ± 0.8 pmol/l) and lowest at 16.00 h (15.5 ± 0.6 pmol/l). In CRF, no significant circadian change was present (22.2 ± 3.1 and 20.4 ± 3.6 pmol/l, respectively), and the nocturnal fall in BP was lost. Our data demonstrate that in CRF the loss and possible reversal of the nocturnal decline in BP is associated with the disappearance of any significant circadian variation in the circulating concentrations of ANP. These findings suggest a role for ANP in the alteration of BP variability of CRF, possibly mediated by autonomic dysfunction, and are further evidence for the existence of a relation between the circadian rhythms of ANP and BP.