Treatment with the Leukotriene Inhibitor Montelukast for 10 Days Attenuates Portal Hypertension in Rat Liver Cirrhosis

The mechanisms underlying intrahepatic vasoconstriction are not fully elucidated. Here we investigated the Kupffer cell (KC)-dependent increase in portal pressure by way of actions of vasoconstrictive cysteinyl leukotrienes (Cys-LTs). Liver cirrhosis was induced in rats by bile duct ligation (BDL for 4 weeks; controls: sham-operation) and thioacetamide application (18 weeks). Infusion of leukotriene (LT) C-4 or LTD4 in isolated perfused livers (20 nM, BDL and sham) demonstrated that LTC4 is a more relevant vasoconstrictor. In BDL animals the Cys-LT1 receptor inhibitor montelukast (1 mu M) reduced the maximal portal perfusion pressure following LTC4 or LTD4 infusion. The infusion of LTC4 or D-4 in vivo (15 mu g/kg b.w.) confirmed LTC4 as the more relevant vasoconstrictor. Activation of KCs with zymosan (150 mu g/mL) in isolated perfused BDL livers increased the portal perfusion pressure markedly, which was attenuated by LT receptor blockade (Ly171883, 20 mu M). Cys-LTs in the effluent perfusate increased with KC activation but less with additional blockade of KCs with gadolinium chloride (10 mg/kg body weight, 48 and 24 hours pretreatment). KCs were isolated from normal rat livers and activated with zymosan or lipopolysaccharide at different timepoints. This resulted in an increase in Cys-LT production that was not influenced by preincubation with montelukast (1 mu M). Infusion of LTC4 (20 nM) and the thromboxane analog U46619 (0.1 mu M) further enhanced portal pressure, indicating additive effects. Treatment with montelukast for 10 days resulted in an impressive reduction in the basal portal pressure and an attenuation of the KC-dependent increase in portal pressure. Conclusion: Activation of isolated KCs produced Cys-LTs. Infusion of Cys-LTs increased portal pressure and, vice versa, treatment with montelukast reduced portal pressure in rat liver cirrhosis. Therefore, montelukast may be of therapeutic benefit for patients with portal hypertension. (HEPATOLOGY 2010;51:2086-2096)