AIM:To determine the role and effect of nitric oxide synthasetype Ⅱ(NOSⅡ) in cirrhotic rats.METHODS:Expression of NOSⅡ mRNA was detected byreal time RT-PCR.The activity of nitric oxide synthase andserum levels of NO,systemic and portal hemodynamicsand degrees of cirrhosis were measured with high sensitivemethods.Chinese traditional medicine tetrandrine was usedto treat cirrhotic rats and to evaluate the function of NO.Double-blind method was applied during the experiment.RESULTS:The concentration of NO and the activity of NOSwere increased markedly at all stages of cirrhosis,andiNOSmRNA was greatly expressed.Meanwhile the portal-venous-pressure (PVP),and portal-venous-flow (PVF) weresignificantly increased.NO,NOS and iNOSmRNA werepositively correlated to the quantity of hepatic fibrosis.Tetrandrine significantly inhibited NO production and theexpression of iNOSmRNA.CONCLUSION:Increased hepatic expression of NOSⅡ isone of the important causes of hepatic cirrhosis and portalhypertension. AIM: To determine the role and effect of nitric oxide synthase type II (NOS II) in cirrhotic rats. METHODS: Expression of NOS II mRNA was detected by real time RT-PCR. The activity of nitric oxide synthase and serum levels of NO, systemic and portal hemodynamics and degrees of cirrhosis were measured with high sensitive method. Chinese traditional medicine tetrandrine was used to treat cirrhotic rats and to evaluate the function of NO. Double-blind method was applied during the experiment .RESULTS: The concentration of NO and the activity of NOSwere increased markedly at all stages of cirrhosis, andiNOS mRNA was greatly expressed. Meanwhile while the portal-venous-pressure (PVP), and portal-venous-flow (PVF) weresignificantly increased.NO, NOS and iNOS mRNA werepositively correlated to the quantity of hepatic fibrosis.Tetalrine significantly inhibited NO production and theexpression of iNOSmRNA.CONCLUSION: Increased hepatic expression of NOSII isone of the important causes of hepatic cirrhosis and portalhyper tension.