BACKGROUND: There is much debate over the regulation of mitochondrial calcium overload and reducing the impairment of energy metabolism in hepatic cells. It has not been reported whether L-arginine (L-Arg) can affect hepatic mitochondrial calcium overload. This study was undertaken to investigate the protective effect of L-Arg on Ca2+ handling of hepatic mitochondrion in rats with obstructive jaundice and to clarify its possible mechanism. METHODS: Seventy-two male SD rats were randomly divided into 3 groups: sham operation+normal saline group (SO group), common bile duct ligation+normal saline group (BDL group), and common bile duct ligation+ L-Arg group (L-Arg group). The levels of malondialdehyde (MDA), superoxide dismutase (SOD) and Ca2+ in rat hepatic mitochondrion were examined at the 7th, 14th and 21st day after operation. RESULTS: The Ca2+ and MDA levels of hepatic mitochondrion increased significantly but their SOD content decreased markedly at each time point in the BDL group. Except at the 21st day, the Ca2+ and MDA, contents of hepatic mitochondrion were significantly lower, and SOD concentrations were higher in the L-Arg group than those in the BDL group at the 7th and 14th day (P<0.01). CONCLUSION: L-Arg has a protective effect on mitochondrion in the early and mid stages of obstructive jaundice. BACKGROUND: There is much debate over the regulation of mitochondrial calcium overload and reducing the impairment of energy metabolism in hepatic cells. It has not been reported whether L-arginine (L-Arg) can affect hepatic mitochondrial calcium overload. This study was undertaken to investigate the protective effect of L-Arg on Ca2 + handling of hepatic mitochondria in rats with obstructive jaundice and to clarify its possible mechanism. METHODS: Seventy-two male SD rats were randomly divided into 3 groups: sham operation + normal saline group (SO group ), common bile duct ligation + normal saline group (BDL group), and common bile duct ligation + L-Arg group (L-Arg group). The levels of malondialdehyde (MDA), superoxide dismutase (SOD) and Ca2 + in rat hepatic mitochondrion were examined at the 7th, 14th and 21st day after operation. RESULTS: The Ca2 + and MDA levels of hepatic mitochondrion increased significantly but their SOD content decreased markedly at each time point in the BDL group . Except at the 21st day, the Ca2 + and MDA, contents of hepatic mitochondria were significantly lower, and SOD concentrations were higher in the L-Arg group than those in the BDL group at the 7th and 14th day (P <0.01). CONCLUSION : L-Arg has a protective effect on mitochondrion in the early and mid stages of obstructive jaundice.