We recently showed that patients with compensated cirrhosis can dispose of their fluid overload while reclining. In contrast, patients with ascites fail to develop supine-induced natriuresis. To assess the effect of reclining on renal sodium handling in patients with advanced cirrhosis and the mechanisms blunting natriuresis in this situation, renal function and plasma concentrations of atrial natriuretic factor, aldosterone and norepinephrine were evaluated in 10 nonazotemic patients with cirrhosis and ascites and 10 healthy controls standing for 2 h and reclining for 2 h. While standing, all patients showed marked sodium retention and significantly elevated plasma atrial natriuretic factor levels, aldosterone and norepinephrine. Glomerular filtration rate did not differ from healthy controls. The reclining increased renal sodium excretion in both groups, but this change was far less marked in patients; natriuresis only rose to the control range in two of them. An increase in atrial natriuretic factor and a depression of plasma aldosterone and norepinephrine was seen in both controls and patients. In the latter, despite the greater change in atrial natriuretic factor and aldosterone, the aldosterone to atrial natriuretic factor ratio, which was inversely correlated with natriuresis during both standing and reclining remained significantly elevated. In the two patients who achieved normal natriuresis during reclining, reclining was associated with both the normalization of the aldosterone/atrial natriuretic factor ratio, and with an increase in glomerular filtration rate. The supine-induced increase in atrial natriuretic factor was not only preserved but was even enhanced in cirrhosis with ascites.(ABSTRACT TRUNCATED AT 250 WORDS)