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

Dual angiotensin receptor and neprilysin inhibitor reduced portal pressure through peripheral vasodilatation and decreasing systemic arterial pressure in cirrhotic rats

BACKGROUND

Portal hypertension develops along with the progression of liver cirrhosis. Natriuretic peptides have been shown to reduce portal pressure but concomitantly activate the renin-angiotensin-aldosterone system (RAAS). Angiotensin receptor-neprilysin inhibitors (ARNIs) upregulate natriuretic peptides and avoid the adverse effects of RAAS activation. ARNIs have been shown to reduce portal pressure in rats with pre-hepatic portal hypertension, which involves relatively little liver injury. This study aimed to evaluate the relevant effects of an ARNI in rats with both liver cirrhosis and portal hypertension.

METHODS

Male Sprague-Dawley rats received common bile duct ligation to induce liver cirrhosis and portal hypertension. Sham-operated rats served as surgical controls. All rats were randomly allocated into three groups to receive distilled water (vehicle), LCZ696 (an ARNI), or valsartan for 4 weeks. Portal hypertension and relevant derangements were assessed after treatment.

RESULTS

Portal hypertension and hyperdynamic circulation developed in the cirrhotic rats. In the rats with cirrhosis and portal hypertension, both LCZ696 and valsartan reduced portal hypertension, mean arterial pressure, and systemic vascular resistance. The decrease in portal pressure was highly associated with the reduction in arterial pressure and systemic vascular resistance. Blood flow in hepatic, splanchnic, and portosystemic collateral systems was not altered. LCZ696 did not significantly influence liver injury or plasma cytokine levels. Liver fibrosis and splanchnic angiogenesis were not affected.

CONCLUSION

ARNI treatment exerted portal pressure lowering effects via peripheral vasodilatation and decreasing systemic arterial pressure in the rats with liver cirrhosis and portal hypertension. Caution should be taken when using ARNIs in liver cirrhosis.

Dual Angiotensin Receptor and Neprilysin Inhibitor Ameliorates Portal Hypertension in Portal Hypertensive Rats

Background: Portal hypertension is characterized by exaggerated activation of the renin-angiotensin-aldosterone axis. Natriuretic peptide system plays a counter-regulatory role, which is modulated by neprilysin. LCZ696 (sacubitril/valsartan) is a dual angiotensin receptor and neprilysin inhibitor. This study evaluated the effect of LCZ696 on portal hypertensive rats. Methods: Portal hypertension was induced by partial portal vein ligation (PVL) in rats. LCZ696, valsartan (angiotensin receptor blocker), or normal saline (control) was administered in PVL rats for 10 days. Then, hemodynamic and biochemistry data were obtained. The hepatic histology and protein expressions were surveyed. On the parallel groups, the portal-systemic shunting degrees were determined. Results: LCZ696 and valsartan reduced mean arterial pressure and systemic vascular resistance. LCZ696, but not valsartan, reduced portal pressure in portal hypertensive rats (control vs. valsartan vs. LCZ696: 15.4 ± 1.6 vs. 14.0 ± 2.3 vs. 12.0 ± 2.0 mmHg, control vs. LCZ696: P < 0.05). LCZ696 and valsartan improved liver biochemistry data and reduced intrahepatic Cluster of Differentiation 68 (CD68)-stained macrophages infiltration. Hepatic endothelin-1 (ET-1) protein expression was downregulated by LCZ696. The portal-systemic shunting was not affected by LCZ696 and valsartan. Conclusion: LCZ696 and valsartan reduced mean arterial pressure through peripheral vasodilation. Furthermore, LCZ696 significantly reduced portal pressure in PVL rats via hepatic ET-1 downregulation.

Neutral endopeptidase (EC 3.4.24.11) in cirrhotic liver: a new target to treat portal hypertension?

BACKGROUND/AIMS

In liver cirrhosis atrial natriuretic peptide (ANP) decreases portal vascular resistance and tributary flow. The enzyme neutral endopeptidase (NEP) degrades ANP and bradykinin and generates endothelin-1 from big-endothelin. We determined the effects of NEP inhibition by candoxatrilat on hormonal status, liver function and arterial and portal pressures in rats with CCl4-induced cirrhosis.

METHODS

Two groups of seven control rats received 1 ml 5% glucose solution alone or containing 10 mg/kg candoxatrilat; three groups of 10 ascitic cirrhotic rats received placebo, 5 or 10 mg/kg candoxatrilat. NEP protein concentration and immunostaining were analyzed in normal and cirrhotic livers.

RESULTS

In cirrhotic rats 10 mg/kg candoxatrilat significantly increased steady-state indocyanine green clearance (a parameter reflecting liver plasma flow) (P<0.01), decreased portal pressure (P<0.01), had no effect on arterial pressure and plasma renin activity but increased ANP plasma levels (P<0.05) and urinary excretions (P<0.01) of ANP and cGMP. In the cytosol fraction of rat cirrhotic livers a 280% increase in NEP content was found (P<0.01), chiefly localized in desmin-positive myofibroblast-like cells of fibrous septa.

CONCLUSIONS

Candoxatrilat has few effects on systemic hemodynamics and hormonal status; its portal hypotensive action depends on effects exerted on intrahepatic vascular resistance.