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

Abstract

Water immersion induced alterations of plasma atrial natriuretic peptide (ANP), circulating plasma volume (PV), plasma sodium and potassium and mean blood pressure (MAP) were examined in 12 patients with non-inflammatory acute renal failure (ARF) and in 15 healthy subjects. In patients with ARF a significantly elevated basal ANP (139 +/- 13 pg/ml versus 75 +/- 4 pg/ml in normals) and elevated MAP (112 +/- 3.5 mmHg versus 87 +/- 2 mmHg in normals) were found. Water immersion induced a significant increase in plasma ANP in both groups, which was significantly more marked in healthy subjects (152 +/- 13 pg/ml) than in patients with ARF (86 +/- 13 pg/ml). Water immersion was accompanied 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 and 4.2 +/- 0.1 mmol/l respectively). In contrast to healthy subjects, in patients with ARF water immersion did not induce enhanced diuresis. In patients with ARF a significantly more marked increase in plasma volume was found than in normals. Data obtained in this study seem to prove preservation of the physiological regulatory mechanism of ANP secretion in ARF patients but reduction of ANP release induced by central volume expansion. The importance of elevated basal plasma values in the maintenance of ARF has not been proven.