[Circadian rhythm of atrial natriuretic peptide, plasma renin and aldosterone activity in healthy subjects and in patients with compensated liver cirrhosis].

The circadian variations in atrial natriuretic peptide (ANP), plasma renin activity (PRA) and plasma aldosterone (PA) have been investigated in a group of 6 patients with compensated cirrhosis of the liver compared with a group of 6 healthy subjects. All studied subjects were kept for a week on standardized life conditions, with a defined daily intake of 120 mEq of sodium and 60 mEq of potassium. Venous blood samples were collected during a whole day at 6, 8, 12, 18, 20 and 24 hours, with the subjects resting in the clinostatic position during the study. Plasma levels of ANP, PRA and PA were determined by radioimmunoassay. The data were analyzed by the cosinor method. The results show that healthy subjects present a significant circadian rhythm for the three biological variables, while patients with cirrhosis of the liver present a significant rhythm for PA only. Acrophase and amplitude of PA do not present any difference between control and patient groups. The levels of PRA and ANP are significantly higher in the cirrhotic patients. These data suggest in cirrhosis a deep variation in the secreting rhythm of PRA and ANP with maintenance, even at higher levels, of intrinsic PA rhythm. This is a possible index of time-related alterations of water-electrolyte balance and cardiovascular processes in liver cirrhosis.