Renal sodium handling and neurohumoral systems in patients with cirrhosis in sitting posture: effects of spironolactone and water immersion.

Renal sodium handling, neurohumoral systems, and systemic hemodynamics were investigated under baseline conditions in sitting posture in 10 healthy subjects, 11 patients with cirrhosis without, and 10 patients with cirrhosis with ascites. Furthermore, the effects of head-out water immersion, 1-week spironolactone administration, or their combination was assessed in the two groups of patients. Patients without ascites exhibited a significant increase in plasma norepinephrine concentration and a tendency toward an increase in plasma aldosterone concentration. Patients with ascites had a significantly lower mean arterial blood pressure despite significant reduction of urinary sodium excretion and fractional sodium excretion as well as an increase of plasma renin activity, plasma aldosterone, and norepinephrine concentration. In patients with ascites, the increase in renal sodium excretion and fractional sodium excretion following water immersion or spironolactone was clearly augmented by the combination of the two maneuvers. The same pattern was observed in patients without ascites. Our findings (a) underscore the importance of studying hemodynamics, renal function, and neurohumoral systems also in upright posture, (b) suggest a role of sympatico-adrenergic activation and proximal sodium retention in preascitic patients, and (c) are compatible with the vasodilation hypothesis of ascites formation.