| 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. It was reported that protection by amino acids (glycine or alanine) against renal hypoxic injury relates to their physicochemical effects , which stabilize kidney tubule membrane protein tertiary structure and protect the mitochondria. The purpose of this study was to elucidate the nephropretective 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: 18 male Sprague-Dawley rats weighing 230+18gm were used in this experiment.2. Methods:1),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 into 3 groups:GroupA :sham operation group(n=6).GroupB:control group(n=6),Group C:amino acids treated group(n=6).Rats were anesthetized with injection (60mg/kg) of pentobarbitone sodium.Animal model: A femoral vein catheter was placed for the adminstration of drugs(at a rate of Iml/lOOg/h). A bladder urine catheter was placed for collecting urine in a tube( 1.5ml),which was weighted previously,tocalculated the urine flow rate. 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 samples were collected after 30, 60, 90, 120> 150, 180minutesofreperfusion.Blood samples were collected from the end of a cut tail after 3 hours,samples were also from portal vein and bilateral nephrectomy were performed after 24 hours of reperfusion. 3).Laboratory measurements: Blood samples -.creatininevalues,BUN level,sodium concentration. Urine samples : creatinine values,sodium concentration,potassium concentration,LDH level,B2-MG level.Creatinine clearance , sodium excretion > potassium excretion > urine flow rate > LDH/cr after 180min of reperfusion.Kidneys from rats were fixed in 10% neutral formalin,and stained with hematoxylin and eosin, examined by standard methods.Histologic studies were scored with semiquantitative scale evaluating changes by pallets standards.Results1.Changes of urine flow rateUrine flow rate increased remarkaly after 60 min reperfusion in amino acids treated group, compared with control group (p<0.05).2.Changes of serum creatinine and BUN values after 24 hours of reperfusionSerum creatinine (85.(T7.7umol/L)and serum BUN concentration (11.4+3.9mmol/L) in amino acids protected rats after 24 hours of reperfusion . were significantly lower(p< 0.01) than those in control rats (Serum creatinine 112.7+ 19.5umol/L and BUN 20.72+. 6.57 mmol/L).3.Change of creatinine excretion,creatinine clearance at 3 hours after reperfusionCreatinine excretion in protected rats was significantly higherthan that in control rats(p<0.05).Creatinine clearance (471+121.5ul/min )in protected rats was significantly higher than thatofcontrol(227.5 "27.0ul/min p<0.01)4.Changes of urine sodium and potassium excreations.Potassium excreation in amino acids treated group at 90,180 min after reperfusion was significantly higher than that of control group(p<0.05). Sodium excretion at 90,1 SOmin after reperfusion in amino acids treated group was significantly higher than that in control (p<0.05)5.Morphologic studiesMorphologic abnomalities including cytoplasmic yacuolization and cell necrosis of the proximal convoluted tubule,tubular lumen obstuction and impairment affecting almost three segments of the promixal convoluted tubule.vascular dilation and congestion and neutrophil infiltration in interstitum were found in control rats. In some kidney of protected rats ,there wre cloudy swelling, granular dege...
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