| It is necessary to block renal circulation temporarily in some complicated renal operations such as nephropyelolithotomy and nephron sparing nephrectomy of renal tumors. How to attenuate renal ischemia- reperfusion injury is a highlight in nephroprotective studies. Some studies have indicated that renal tissue ET-1 level was increased and renal tubular apoptosis was the main way of death in renal post-ischemic reperfusion. It was reported that protection by amino acids (glycine or alanine ) against renal hypoxic injury relates to their physicochemical effects, which stabilized kidney tubule membrane protein tertiary structure and protect the mitochondria. The purpose of this study was to elucidate the nephroprotective effects on renal ischemia-reperfusion injury from a mixture of 8 L-amino acids and the possible mechanism of nephroprotection by this amino acid mixture.Materials and Methods1. Animals: 60 male Sprague-Dawley rats weighing 240?0gm were used in this experiment.2. Methods1) Preparation of a mixture of 8 L-amino acids: 8 L-amino acids (glycine, alanine et al.)were dissolved, asepticized for preparation.2) Animal experimentAnimal groups: Rats were randomly divided in to 3 groups: group A (sham operated group, n=8^ group B (control group, n=26 )* group C (amino acids treated group, n=26 ).Animal model: A femoral vein catheter was placed for the administration of drugs (at a rate of 1 ml/lOOg/h ). A bladder urine catheter was placed for collecting urine in a tube (1.5 ml), which was weighted previously. After a hour infusion, a midline incision was made, the renal pedicles were occluded with a nontraumatic clamps for 45 minutes. Sham-operated group was not occluded. Urine and blood samples were collected after 3 hours of reperfusion, and blood samples were obtained from the end of a cut tail. After 24 hours of reperfusion blood samples were collected from portal vein. Rats were killed and left nephrectomy were performed after 45 minute ischemia and 15 minute ^ 3 and 24 hour after reperfusion, respectively.3) Laboratory measurements Blood samples: creatinine values, Bun level. Urine samples: creatinine values, sodium and potassium concentration, creatinine clearance after 3 hour of reperfusion. Renal tissue ET-1 assay: ET-1 levels in renal tissue were determined by radioimmuno assay (RIA). The procedure was done as described in the ET-1 RIA Kit. Renal cell apoptosis-assay: Designed to utilize flowcytometry to quantitatively determine the percentage of cells undogoing apoptosis. Three populations of cells can be quantified: Viable (no staining), early apoptotic (Annexin V positive) and late apoptotic/necrotic (Annexin V and propidium idodide positive).Results1. Changes of urine serum creatinine and Bun values after 3 and 24 hours of reperfusionserum creatinine (45? umol/L ) and serum Bun concentration (15.83 + 2.52mmol/L ) in amino acids protected rats after 3 hours of reperfusion were significantly lower (PO.01 ) than those in control rats (serum creatinine 74 ? umol/L and Bun 25.45 + 5.10 mmol/L ). After 24 hours of reperfusion the Bun values (16.06?.21 mmol/L ) were lower (PO.01 ) than those in the control rats (Bun 24.18 ?4.97 mmol/L).2. Changes of urine creatinine excretion, creatinine clearance at 3 hours after reperfusionCreatinine excretion in protected rats was significantly higher than that in control rats (PO.01). Creatinine clearance (699.33 ?7.7 ul/min ) in protected rats was significantly higher than that of control (191.03+36.3 ul/min P<0.01).3. Changes of urine sodium and potassium excretionUrine sodium and potassium excretion in amino acids treated group at 3 hour after reperfusion were lower than those in control group (PO.01).4. Changes of renal tissue ET-1 LevelThe renal tissue ET-1 levels at 45 min ischemia ^ 15 min and 3 h reperfusion in control group were respectively 7.34 + 2^ 10.07 ?2.76 > 13.00 + 2.69 (pg/mg), which were obviously different (PO.05). ET-1 levels at 15 min and 3 h aft... |
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