The
natriuretic effect of
atrial natriuretic peptide (
ANP) is blunted in certain clinical disorders such as
congestive heart failure and
liver cirrhosis, despite the elevated plasma
ANP levels. These
sodium-retaining states are characterized by increased activity of the renal sympathetic nerves. Recent studies have shown higher levels of circulating and urinary
catecholamines in
cancer patients. We hypothesized that the increased
adrenergic activity may be responsible for
ascites formation in patients with
peritonitis carcinomatosa (PC). The objective of this study was to determine the renal responses to endogenous
ANP in patients with PC. Patients, hospitalized at our institute for PC, were examined using renal clearance studies for 2 h. Non-
cancer patients were also examined as control subjects. Statistical analysis was performed using Wilcoxon's rank sum test. The results showed that absolute and fractional
sodium excretions were markedly lower in patients with PC (54 +/- 16 microEq/min, means +/- SE, p < 0.0005; 0.55 +/- 0.15%, p < 0.005) than in control patients (166 +/- 14 microEql/min; 1.14 +/- 0.09%, respectively). Plasma
ANP concentration was increased in patients with PC (34.7 +/- 8.4 pg/ml, p < 0.001) in comparison with control patients (13.3 +/- 2.0 pg/ml). Plasma and urinary levels of
norepinephrine were significantly higher in
cancer patients (0.36 +/- 0.10 ng/ml, p < 0.05; 125 +/- 20 ng/dl GF, p < 0.05) than in the controls (0.17 +/- 0.02 ng/ml; 73 +/- 13 ng/dl GF). These results suggest that increased renal sympathetic nerve activity may contribute to the attenuation of the
natriuretic effect of
ANP in patients with PC.