BACKGROUND: Obstructive jaundice is a common disease. Acute renal injury, secondary to obstructive jaundice, is one of the main causes of postoperative multiple system failure. This investigation evaluated renal function and renal aquaporin 2 (AQP2) expression changes in obstructive jaundice. METHODS: Forty male Wistar rats were equally randomized into two groups. Twenty in the obstructive jaundice group were subjected to common bile duct ligation, and then were subdivided into 7-and 14-day obstruction groups, and the other 20 sham-operated rats were also subdivided into 7-and 14-day groups. At the end of each experiment, rats were sacrificed, venous blood was collected from the inferior vena cava, and serum creatinine and urine nitrogen concentrations were measured. At the same time, the medulla of the right kidney was separated and AQP2 expression was assessed. The RT-PCR technique was used to detect AQP2 mRNA expression. RESULTS: Ligation of the common bile duct caused significant rises in serum bilirubin, creatinine clearance and urine nitrogen. AQP2 expression in the medulla decreased mere significantly (38.35±2.08) in the 7-day ligation group than in the sham-operated group (41.06± 1.04), as did that in the 14-day ligation group, even more than (31.89±1.57). The expression of AQP2 mRNA also decreased more significantly in the 14-day group (0.5429± 0.1107) than in the 7-day group (0.6071±0.1328).CONCLUSION: AQP2 expression is inhibited in obstructive jaundice, and so is its gene expression. BACKGROUND: Obstructive jaundice is a common disease. Acute renal injury, secondary to obstructive jaundice, is one of the major causes of postoperative multiple system failure. This investigation as renal function and renal aquaporin 2 (AQP2) expression changes in obstructive jaundice. METHODS: Forty male Wistar rats were equally randomized into two groups. Twenty in the obstructive jaundice group were subjected to common bile duct ligation, and then were were subdivided into 7-and 14-day obstruction groups, and the other 20 sham-operated rats were also subdivided At the end of each experiment, rats were sacrificed, venous blood was collected from the inferior vena cava, and serum creatinine and urine nitrogen concentrations were measured. At the same time, the medulla of the right kidney was separated and AQP2 expression was assessed. The RT-PCR technique was used to detect AQP2 mRNA expression. RESULTS: Ligation of the common bile duct caused significant r ises in serum bilirubin, creatinine clearance and urine nitrogen. AQP2 expression in the medulla decreased mere significantly (38.35 ± 2.08) in the 7-day ligation group than in the sham-operated group (41.06 ± 1.04), as did that in the 14 -day ligation group, even more than (31.89 ± 1.57). The expression of AQP2 mRNA also decreased more significantly in the 14-day group (0.5429 ± 0.1107) than in the 7-day group (0.6071 ± 0.1328). CONCLUSION: AQP2 expression is inhibited in obstructive jaundice, and so is its gene expression.