Objective:To investigate nephroprotective effec ts of a mixture of 8 L-amino acids on renal ischemia-reperfusion injury and it s effects on renal endothelin-1 (ET-1). Methods:The mixture of 8 L-amino acids includes glycine, alan ine, threonine, serine, valine, leucine, isoleucine and proline. Acute ischemic renal injury was induced by clamping renal pedicle for 45 minutes in rats. Sixt y male Sprague-Dawley rats were randomly divided into 3 groups: a sham-operate d group (Group A, n=8), a control group (Group B, n=26) and an amino acid-treat ed group (Group C, n=26). Amino acids were infused at a rate of 1 ml·100g -1 ·h -1 I hour before ischemia and during 3 hours of the whole reperfusio n. The serum creatinine values, BUN levels, creatinine clearance, urine sodium & potassium excretion, urine lactate dehydrogenase (LDH), the rate of urine flow and histological examination were measured. Renal ET-1 levels were assayed wit h radioimmunological assay (RIA) Results: The creatinine clearance was 471.0 μl/min ± 121 .5 μl/min in Group C and 227.0 μl/min± 27.0 μl/min in Group B 3 ho urs after reperfusion, P< 0.01 ). The urine flow rate w as 63.6 μl/min± 15.2 μl/min in Group C and 24.3 μl/min± 7.7 μ l/min in Group B, P< 0.01 ) 1.5 hours after reperfu sion. The serum creatinine was 85.0 μl/min± 7.7 μmol/L and BUN concent ration 11.4 mmol/L ± 3.9 mmol/L in Group C and 112.7 μmol/L± 19.5 μmol/L and 20.7 mmol/L± 6.6 mmol/L respectively in Group B after 24 hours of reperfusion (P< 0.05 ) . The mean histological score by standards of Paller in kidneys was 108.7 ± 15.7 in Group C, and 16 8.8 ± 14.8 in Group B (P< 0.01 ).The renal ET-1 lev els 15 minute and 3 hours after reperfusion were 7.2 pg/mg± 0.8 pg/mg an d 9.6 pg/ml± 1.0 pg/ml in Group C , and 10.1 pg/ml± 2.8 pg/ml a nd 13.0 pg/ml± 2.7 pg/ml in Group B (P< 0.01 ). Conclusions:The mixture of 8 L-amino acids can provide remar kable protection against renal ischemia-reperfusion injury in rats. This may as sociate with attenuation of renal ET-1 disorder. Objective: To investigate nephroprotective effector ts of a mixture of 8 L-amino acids on renal ischemia-reperfusion injury and it s effects on renal endothelin-1 (ET-1). Methods: The mixture of 8 L-amino acids includes glycine, alan ine, threonine, serine, valine, leucine, isoleucine and proline. Acute ischemic renal injury was induced by clamping renal pedicle for 45 minutes in rats. Sixt y male Sprague-Dawley rats were randomly divided into 3 groups: a sham-operate d A Group A, n = 8, a control group (Group B, n = 26) and an amino acid-treat group (Group C, n = 26). Amino acids were infused at a rate of 1 ml · 100 g -1 · h -1 I hour before ischemia and during 3 hours of the whole reperfusio n. The serum creatinine values, BUN levels, creatinine clearance, urine sodium & potassium excretion, urine lactate dehydrogenase (LDH), the rate of urine flow and histological examination were measured. Renal ET-1 levels were assayed wit h radioimmunological assay (RIA) Results: The crea tinine clearance was 471.0 μl / min ± 121.5 μl / min in Group C and 227.0 μl / min ± 27.0 μl / min in Group B for 3 hrs after reperfusion, P <0.01). The urine flow rate w as 63.6 μl / min ± 15.2 μl / min in Group C and 24.3 μl / min ± 7.7 μl / min in Group B, P <0.01) 1.5 hours after reperfu sion. The serum creatinine was 85.0 μl / min ± 7.7 μmol / L and BUN concentrator ration 11.4 mmol / L ± 3.9 mmol / L in Group C and 112.7 μmol / L ± 19.5 μmol / L and 20.7 mmol / L ± 6.6 mmol / L respectively in Group B after 24 hours of reperfusion (P <0.05). histological score by standards of Paller in kidneys was 108.7 ± 15.7 in Group C, and 16 8.8 ± 14.8 in Group B (P <0.01). The renal ET-1 lev els 15 minutes and 3 hours after reperfusion were 7.2 pg / mg ± 0.8 pg / mg an d 9.6 pg / ml ± 1.0 pg / ml in Group C and 10.1 pg / ml ± 2.8 pg / ml a nd 13.0 pg / ml ± 2.7 pg / ml in Group B (P <0.01) : The mixture of 8 L-amino acids can provide remar kable protection against renal ischemia-reperfusion injury in rats. This may as sociate with attenuation of renal ET-1 disorder.