Abstract:Objective： To explore the regulating mechanism of inducible nitric oxide synthase(iNOS) in hepatic injury of obstructive jaundice (OJ) in vivo and in vitro experiments. Methods：(1) Rat hepatocytes were isolated by in situ collagenase perfusion and primary culture. Hepatocytes were pretreated with various concentrations of iNOS inhibitor SMT for 20 min. After pretreatment, 50μM GCDC was added for an additional 24hr. Cells were next detected by FCM and TUNEL.(2) Experimental obstructive jaundice (BDL) was induced by double ligation of the bile duct in rats. After BDL for 3d、7d、14d、and 21d, the apoptotic status in liver of all rats were determined with TUNEL, and iNOS protein in liver of OJ was ditermined with immunohistochemistry method. Results：(1) SMT decreased GCDC-induced apoptosis in a concentration - dependent manner. (2) The apoptotic rate of liver was related to length of time of OJ. Apoptosis index (AI) was highest from rats with 14d bile duct ligation. The stronger the iNOS expression, the higher was the number of apoptotic cells that was found in OJ. Conclusions：iNOS is involved in the regulation and the occurrence and progression of hepatic injury of obstructive jaundice.