Haemodynamic responses to a ring-deleted analogue of atrial natriuretic peptide in rats with cirrhosis

Aims: In cirrhosis, the effects of selective activation of atrial natriuret ic peptide (ANP) R2-receptors on haemodynamics, endogenous ANP (ANP1-28) an d sodium excretion are unknown. The aim of the present study was to examine the effects of selective activation of ANP-R2 receptors by ANP4-23 (a ring -deleted analogue of endogenous ANP) on haemodynamics, plasma ANP1-28 conce ntrations and urinary sodium excretion in conscious cirrhotic and normal ra ts. Methods: Haemodynamics and sodium excretion were measured prior to and following administration of ANP4-23. Plasma ANP1-28 concentrations were als o measured. Results: In cirrhotic rats, ANP4-23 significantly decreased por tal pressure and tributary blood flow by 15% and 25%, respectively but sign ificantly increased portal territory vascular resistance by 30%. Systemic a nd renal haemodynamics were not altered by ANP4-23, In normal rats, ANP4-23 did not significantly change splanchnic, renal and systemic haemodynamics. In both groups of rats, ANP4-23 increased plasma ANP1-28 concentrations bu t did not change sodium excretion. Conclusions: ANP4-23 administration indu ced splanchnic vasoconstriction in cirrhotic but not in normal rats. ANP4-2 3-elicited vasoconstriction caused a portal hypotensive effect in cirrhotic rats. Finally, in both groups, ANP4-23 caused an increase in plasma ANP1-2 8 concentrations but did not increase sodium excretion.