Background/aims: Patients with cirrhosis and ascites show high plasma concentrations of endothelin. The aim of the current study was to investigate whether this feature is a compensatory response to effective hypovolemia or a consequence of systemic endotoxemia.
Methods: Protocols 1 and 2 assess the effect of acute changes in effective blood volume on plasma endothelin, and protocol 3 investigates the relationship between plasma endotoxin and endothelin in patients with cirrhosis and ascites. Protocol 1 included nine healthy subjects and 26 patients with cirrhosis studied during supine rest, upright tilt (which decreases effective blood volume) and cycloergometric exercise (which activates vasoactive systems by a baroreceptor independent mechanism). Protocol 2 included six patients studied before and 1 and 3 h after the intravenous administration of a plasma expander. In protocol 3, the plasma levels of endothelin and endotoxin were measured in 17 non-infected patients with cirrhosis and also in four patients with spontaneous bacterial peritonitis at diagnosis and following resolution of infection.
Results: Plasma endothelin was 3-5 times higher in patients with cirrhosis than in healthy volunteers. In healthy subjects, upright tilt and exercise were associated with a significant activation of the renin-aldosterone and sympathetic nervous systems and an increase in plasma endothelin. In patients with cirrhosis, upright tilt and exercise were associated with a significant increase and plasma volume expansion with a marked suppression of the renin-aldosterone and sympathetic nervous systems. However, in these patients none of these maneuvers affected plasma endothelin levels. In the patients with cirrhosis in protocol 3, there was no correlation between plasma endotoxin and endothelin. Resolution of peritonitis was associated with a marked fall in plasma endotoxin and no changes in plasma endothelin.
Conclusions: These findings suggest that mechanisms other than effective hypovolemia or systemic endotoxemia are involved in the increased plasma endothelin of cirrhosis with ascites.