Evaluation Of L-arginine On Renal Ischemia-reperfusion Injury In Rats By Contrast-enhanced Ultrasound

Objective:Quantitative evaluation of the effect of L-arginine on renal cortical blood perfusion in rats with renal ischemia reperfusion injury by contrast-enhanced ultrasound(CEUS).To analyze the correlation between quantitative parameters of renal cortical time-intensity curve(TIC)and biochemical parameters,and to evaluate effects of L-arginine on rat vascular endothelial growth factor(VEGF)and cysteine aspartic protease 1(Caspase-1)expression.To explore the value of contrast-enhanced ultrasound in evaluating the efficacy of drug intervention in renal ischemia-reperfusion injury.Methods:Twenty-four healthy adult male SD rats were randomly divided into sham operation group(S group),ischemia-reperfusion group(I/R group)and L-arginine group(L-arg group),8 rats in each group.In the S group,only the right kidney was excised.In the I/R group and the L-arg group,the left kidney pedicle was clamp and the left kidney ischemia-reperfusion injury model was prepared.L-arg group was injected with L-arginine injection 300mg/kg before ischemia 30 minutes and the same amount of normal saline was injected into the S group and I/R group via the tail vein.Two-dimensional ultrasound and contrast-enhanced ultrasound were performed 24 hours after reperfusion.The left kidney size and renal cortical thickness were measured by conventional two-dimensional ultrasound,followed by contrast-enhanced ultrasound.Quantitative analysis of renal cortical region of interest(ROI)TIC curves and parameters using analysis software.Analysis parameters include peak intensity(PI),time to peak(TTP),area under the curve(AUC)and mean transit time(MTT).After the end of the angiography,blood samples were collected for determination of serum creatinine(SCr),blood urea nitrogen(BUN),serum cystatin C(SCys-C),alanine aminotransferase(ALT)and aspartate aminotransferase(AST)concentrations.The left kidney and liver tissues were removed after the blood was taken.Liver and some kidney tissues were made into paraffin sections and pathological observation was performed after HE staining,some kidney tissues were stored at-80℃for storage.The expression of Caspase-1 in renal tissues was detected by immunohistochemistry and the expression of VEGF mRNA in renal tissues was detected by real-time quantitative PCR.Statistical analysis was performed by one-way ANOVA.The bivariate Pearson correlation analysis was used to analyze the correlation between the quantitative parameters of the TIC curve and relevant laboratory indicators.Results:In the experiment,the rats in each group had good anesthesia effect,the modeling and angiography were smooth.1.Two dimensional ultrasound showed that the left kidney had clear outline,regular shape,intact capsule and uniform echo.The kidney size and renal cortex thickness of each group were as follows:(1)S group:the size of the kidney is about(15.98±0.35)×(10.19±0.35)mm~2 and the thickness of the cortex is about(2.08±0.15)mm.(2)I/R group:the size of the kidney is about(17.16±0.50)×(10.70±0.45)mm~2 and the thickness of the cortex is about(2.30±0.15)mm.(3)L-arg group:kidney size is about(16.49±0.45)×(10.39±0.24)mm~2 and the thickness of the cortex is about(2.18±0.20)mm.The results of pairwise comparison between groups showed that the left kidney length of I/R group and L-arg group increased compared with S group,and the left kidney length of L-arg group decreased compared with I/R group,the difference was statistically significant(P<0.05).The left anteroposterior diameter and cortical thickness of the I/R group were significantly higher than those of the S group(P<0.05).There were no significant differences in the anteroposterior diameter and renal cortical thickness between the S group and the L-arg group,the I/R group and the L-arg group.2.There were significant differences in TTP,AUC and MTT between the three groups.Compared with S group,TTP and MTT prolonged and AUC increased in I/R group and L-arg group(P<0.05).Compared with I/R group,TTP and MTT were shortened and AUC decreased in L-arg group(P<0.05).The PI value of L-arg group was higher than that of I/R group(P<0.05).There was no significant difference in PI between S group and L-arg group,S group and I/R group.3.Compared with S group,the SCr,BUN,SCys-C,ALT and AST in I/R group and L-arg group were significantly increased(P<0.05).Compared with I/R group,the SCr,BUN and SCys-C in L-arg group decreased,the ALT level increased(P<0.05);there was no difference in AST between I/R group and L-arg group.4.The expression of VEGF and Caspase-1 in renal tissue increased during ischemia-reperfusion.L-arginine significantly up-regulated the expression of VEGF and inhibited the expression of Caspase-1.5.Bivariate Pearson linear correlation analysis showed that the TIC curve parameters TTP,MTT,AUC and laboratory biochemical indicators were correlated,and TTP was highly positively correlated with SCr,BUN and SCys-C(r=0.899,0.847,0.819,P=0.000,0.000,0.000),AUC was highly positively correlated with SCr(r=0.828,P=0.000),and MTT was highly positively correlated with SCr(r=0.849,P=0.000);AUC and BUN,SCys-C were Moderate correlation(r=0.733,0.785,P=0.000,0.000),MTT was moderately correlated with BUN and SCys-C(r=0.765,0.789,P=0.000,0.000).Parameters PI and biochemistry of TIC curve The indicators are no relevant.Conclusions:1.Contrast-enhanced ultrasound can quantitatively reflect renal cortical blood perfusion information before and after renal ischemia reperfusion injury in rats,and quantitatively evaluate the effect of L-arginine on renal cortical blood perfusion in ischemia-reperfusion.2.Contrast parameters combined with laboratory biochemical examination can effectively and sensitively reflect the degree of renal dysfunction of ischemia-reperfusion.TTP,MTT and AUC have reference significance.3.L-arginine can alleviate renal ischemia-reperfusion injury in rats by up-regulating the expression of VEGF in kidney tissue and inhibiting the expression of Caspase-1.