HIGH PLASMA-LEVELS OF ATRIAL-NATRIURETIC-PEPTIDE IN PREASCITIC CIRRHOSIS - INDIRECT EVIDENCE OF REDUCED NATRIURETIC EFFECTIVENESS OF THE PEPTIDE

Controversial results come from spot measurements of plasma atrial nat riuretic peptide (ANP) in compensated cirrhotic patients. Moreover, ei ther blunted or exaggerated natriuresis has been described after maneu vers increasing plasma ANP. This does not make it possible to delineat e the ANP effectiveness. Plasma ANP, renin activity (PRA) and aldoster one and hematocrit were serially measured (7 AM, 9 AM, 6 PM, and 11 PM ) in nine preascitic cirrhotic outpatients and in nine healthy subject s on normal sodium diet (150 mmol/day) and carrying on their usual act ivities (mobile from 7 AM to 10 PM). Daily natriuresis was monitored t he day before and during the study. In both groups, ANP peaked at the end of the recumbence period (7 AM) and declined on the assumption of the upright position, so that both ANP values of the standing period w ere significantly lower than the mean daily level. These fluctuations were reciprocal to PRA and hematocrit changes. Patients showed steadil y elevated plasma ANP and reduced PRA (ANP mean daily level: 33.3 +/- 3.8 vs. 15.5 +/- 3.2 pg/mL, P = .004; PRA: 0.76 +/- 0.23 vs. 1.66 +/- 0.21 ng/mL/hr, P = .003). Aldosterone fluctuations and mean daily leve l were similar in the two groups (mean daily level: 122 +/- 11 vs. 119 +/- 9 pg/mL). Natriuresis was well adapted to the sodium intake and s imilar in healthy subjects (day 1: 152 +/- 11 mmol; day 2: 138 +/- 12. 5 mmol) and patients (143 +/- 15 mmol; 148 +/- 29 mmol). Preascitic ci rrhotic patients on a normal salt intake and carrying on their usual a ctivities develop a new steady state requiring increased AMP levels to maintain a sodium balance. In addition to a reduced renal sensitivity to ANP, several subtle abnormalities of the antinatriuretic forces ma y yield the renal hyporesponsiveness to the peptide.