In vivo gene transfer of endothelial nitric oxide synthase decreases portal pressure in anaesthetised carbon tetrachloride cirrhotic rats

Abstract

Background: Portal hypertension in cirrhosis results from enhanced intrahepatic resistance to an augmented inflow. The former is partly due to an imbalance between intrahepatic vasoconstriction and vasodilatation. Enhanced endothelin-1 and decreased activity of hepatic constitutive endothelial nitric oxide synthase (NOS 3) was reported in carbon tetrachloride (CCl 4 ) cirrhotic rat liver. Aims: To study whether an increase in hepatic NOS 3 could be obtained in the CCl 4 cirrhotic rat liver by in vivo cDNA transfer and to investigate a possible effect on portal pressure. Methods: Hepatic NOS 3 immunohistochemistry and western blotting were used to measure the amount of NOS 3 protein. Recombinant adenovirus, carrying cDNA encoding human NOS 3, was injected into the portal vein of CCl 4 cirrhotic rats. Cirrhotic controls received carrier buffer, naked adenovirus, or adenovirus carrying the lac Z gene. Results: NOS 3 immunoreactivity and amount of protein (western blotting) were significantly decreased in CCl 4 cirrhotic livers. Following cDNA transfer, NOS 3 expression and the amount of protein were partially restored. Portal pressure was 11.4 (1.6) mm Hg in untreated cirrhotic (n=9) and 11.8 (0.6) in lac Z transfected (n=4) cirrhotic rats but was reduced to 7.8 (1.0) mm Hg (n=9) five days after NOS 3 cDNA transfer. No changes were observed in systemic haemodynamics, in liver tests or urinary nitrates, or in NOS 3 expression in lung or kidney, indicating a highly selective transfer. Conclusions: NOS 3 cDNA transfer to cirrhotic rat liver is feasible and the increase in hepatic NOS 3 leads to a marked decrease in portal hypertension without systemic effects. These data indicate a major haemodynamic role of intrahepatic NOS 3 in the pathogenesis of portal hypertension in CCl 4 cirrhosis.

Atorvastatin lowers portal pressure in cirrhotic rats by inhibition of RhoA/Rho-kinase and activation of endothelial nitric oxide synthase

“…43,44 Furthermore, clinical trials have been performed to decrease intrahepatic vascular tone by inhibition of ␣-adrenoceptormediated pathways. 45 However, all these treatment strategies either have not been shown to sufficiently decrease portal pressure or are not applicable in a clinical setting.…”

A role for asymmetric dimethylarginine in the pathophysiology of portal hypertension in rats with biliary cirrhosis†‡

“…Measurements were performed under pentobarbital anesthesia (100 L/100 g body weight) to allow cannulation of the right carotid artery and the portal vein, as previously described. 8,18 Biochemical Analysis. Blood taken via cardiac puncture was collected in Vacutainer tubes (Becton-Dickinson, Erembodegem, Belgium).…”

“…For eNOS immunohistochemistry, a three-step indirect immunoperoxidase method was applied as previously described. 8 Intensity of sinusoidal staining was scored blindly using a semiquantitative scale: 0, no; ϩ1, weak; ϩ2, moderate; and ϩ3, strong reactivity. For each specimen, 10 different high-power fields were scored; the mean value was taken as the final score.…”

“…[4][5][6][7] The molecular basis of intrahepatic NO deficiency has consistently been attributed to a decreased activity of endothelial NO synthase (eNOS). [4][5][6]8 However, the mechanisms of this endothelial dysfunction remain illdefined and may vary depending on the cause of the underlying liver disease. [8][9][10] In the early 1990s, Vallance and colleagues 11 showed that NO synthesis could be inhibited by the endogenous circulating amino acid asymmetric dimethylarginine (ADMA).…”

“…[4][5][6]8 However, the mechanisms of this endothelial dysfunction remain illdefined and may vary depending on the cause of the underlying liver disease. [8][9][10] In the early 1990s, Vallance and colleagues 11 showed that NO synthesis could be inhibited by the endogenous circulating amino acid asymmetric dimethylarginine (ADMA). ADMA and its vasoinactive stereoisomer, symmetric dimethylarginine (SDMA), are synthesized via enzymatic methylation of L-arginine residues in proteins and are released during proteolysis.…”