Blunted natriuresis and abnormal systemic hemodynamic responses to C-type and brain natriuretic peptides in rats with cirrhosis

Background/Aims: The effects of C-type and brain natriuretic peptides (CNP and BNP, respectively) on renal excretion of sodium and hemodynamics have not yet been studied in cirrhosis. Methods: This study aimed to examine the effects of saline, CNP (300 ng • kg−1; min−1 • min−1 i.v. for 30 min) and BNP (600 ng • kg−1 • min−1 i.v. for 30 min) on natriuresis and diuresis in normal and rats with cirrhosis. Moreover, regional and systemic hemodynamics were measured prior to and following CNP and BNP administration in normal rats and rats with cirrhosis with ascites. Results: In rats with cirrhosis, the effects of CNP or BNP on natriuresis and diuresis did not significantly differ from the effects of saline. CNP significantly decreased portal pressure and systemic vascular resistance and significantly increased the cardiac index. BNP significantly decreased portal tributary blood flow, portal pressure and cardiac index. In normal rats, natriuresis and diuresis were signifiantly higher with CNP and BNP than with saline. Systemic hemodynamics were not changed by CNP. A decrease in arterial pressure was the sole BNP-induced hemodynamic change. Conclusions: In conclusion, this study shows that the natriuretic response to pharmacological doses of CNP and BP is blunted in rats with cirrhosis. This blunting may be related to an activation of the endogeneous antinatriuretic systems secondary to systemic vasodilation (by CNP) or to a decreased cardiac index (by BNP). Finally, this study shows that CNP and BNP have a portal hypotensive action.