RESISTANCE TO NATRIURESIS IN PATIENTS WITH PERITONITIS CARCINOMATOSA

The natriuretic effect of atrial natriuretic peptide (ANP) is blunted in certain clinical disorders such as congestive heart failure and liv er cirrhosis, despite the elevated plasma ANP levels. These sodium-ret aining states are characterized by increased activity of the renal sym pathetic nerves. Recent studies have shown higher levels of circulatin g and urinary catecholamines in cancer patients. We hypothesized that the increased adrenergic activity may be responsible for ascites forma tion 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 w ere also examined as control subjects. Statistical analysis was perfor med using Wilcoxon's rank sum test. The results showed that absolute a nd fractional sodium excretions were markedly lower in patients with P C (54 +/- 16 mu Eq/min. means +/- SE, p < 0.0005; 0.55 +/- 0.15 %, p < 0.005) than in control patients (166 +/- 14 mu Eql/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 pat ients (13.3 +/- 2.0 pg/ml). Plasma and urinary levels of norepinephrin e 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.