Water Immersion Induced Alterations of Atrial Natriuretic Peptide in Patients with Non-Inflammatory Acute Renal Failure

Water immersion induced alterations of plasma atrial natriureticpeptide (ANP), circulating plasma volume (PV), plasma sodiumand potassium and mean blood pressure (MAP) were examined in12 patients with non-inflammatory acute renal failure (ARF)and in 15 healthy subjecs. In patients with ARF a significantlyelevated basal ANP (139±13 pg/ml versus 75±4 pg/mlin normals) and elevated MAP (112±3.5 mmHg versus 87±2mmHg in normals) were found. Water immersion induced a significantincrease in plasma ANP in both groups, which was significantlymore marked in healthy subjects (152±13 pg/ml) than inpatients with ARF (86±13 pg/ml). Water immersion wasaccompanied by a significantly more marked reduction of MAP(23±3 mmHg) and plasma sodium (6.1±0.6 mmol/l)in patients with ARF than in normals(12.7±1.5 mmHg and4.2±0.1 mmol/l respectively). In contrast to healthysubjects, in patients with ARF water immersion did not induceenhanced diuresis. In patients with ARF a significantly moremarked increase in plasma volume was found than in normals.Data obtained in this study seem to prove preservation of thephysiological regulatory mechanism of ANP secretion in ARF patientsbut reduction of ANP release induced by central volume expansion.The importance of elevated basal plasma values in the maintenanceof ARF has not been proven.