OBJECTIVETo study the relationship between the dynamic changes of caveolin-1 with the degrees of liver fibrosis and portal venous pressure (PVP) in the process of rat liver cirrhosis formation induced by dimethylnitrosamine (DMN); also to investigate the mechanisms of caveolin-1 in the regulation of endothelial nitric oxide synthase (eNOS).

METHODSLiver cirrhosis was induced in rats by DMN. The degrees of liver fibrosis and PVP were measured. NOS activity was assessed by citrulline generation. Protein expressions of caveolin-1, eNOS and caveolin-1-eNOS interactions were examined by Western blot and immunoprecipitation, respectively.

RESULTSFour weeks after DMN administration, liver fibrosis was at its peak and then decreased gradually. Immunoprecipitation and Western blot demonstrated that there was enhanced binding of caveolin-1 with eNOS in the process of rat liver cirrhosis. An increase in caveolin-1 expression was detected but the expression of eNOS was lower in cirrhotic tissues than in normal liver tissues. Caveolin-1 protein levels were positively correlated with the degrees of liver fibrosis and the levels of PVP (r=0.967, P < 0.01; r=0.922, P < 0.01, respectively), while NOS catalytic activity was negatively correlated with the degrees of liver fibrosis and levels of PVP (r= 0.973, P < 0.01; r=-0.947, P < 0.01) respectively.

CONCLUSIONSCaveolin-1 upregulation is associated with the development of portal hypertension in liver cirrhosis. Over-expression of caveolin-1 in perisinusoidal cells may promote caveolin-1-eNOS binding and reduce the activity of eNOS.