Inhibiting Effects Of Angiotensin Converting Enzyme Inhibitors On Aldose Reductase Activity

Objective:To investigate the impact of ACEI such as captopril,lisinopril, benazepril,Lei enalapril on aldose reductase,and the effect of captopril and lisinopril on the activity of AR from cardiac muscle of SHR rats.Methods:1.Aldose reductase was extracted from normal cattle lens,and the method was used to optimize the determination of aldose reductase activity. Brad-ford staining method was used in the determination of rough-AR protein concentration,while Tris-glycine SDS polyacrylamide gel electrophoresis was used for analysis of the rough-AR.DL-glyceraldehyde was mixed with the other components at 25℃for 10 minutes,in which DL-glyceraldehyde served as the substrate and NADPH as coenzyme.Then 5 mmol·L-1 DL-glyceraldehyde was added to start the enzymatic reaction and a 5 minutes continuous monitoring of changes in absorbance of the response system was conducted in 340nm at 25℃, under the definition that one activity units(AU) represents 0.001 decline of the absorbance per minute at 25℃.We changed the concentration of NADPH, substrate DL-glyceraldehyde concentration and amount of AR enzyme,and the consequential impact on aldose reductase enzyme reaction system was observed, while concentrations of the other components were maintained invariably,and non-substrate sample served as control.2.In vitro,we compared inhibitory action of captopril,lisinopril,benazepril,Ray enalapril on aldose reductase,in which epalrestat served as positive control.3.In vivo,ultraviolet spectrophotometry was performed to determine the activity of AR from cardiac muscle of SHR rats pre-treated by captopril and lisinopril:distilled water(negative control),captopril(50 mg·kg^-1·d^-1),Lisinopril(20 mg·kg^-1·d^-1).18 SHR rats was divided randomly into 3 groups,6 rats for each..Absorption spectrometry and immumofluorescence method were performed to determine the content of AngⅡ.Results:1.NADPH concentration,DL-glyceraldehyde-concentration,and amount of AR have affected the activity of aldose reductase.Post optimization of aldose reductase enzyme reaction system were as follows:NADPH concentration, 0.25 mmol·L^-1,DL-glyceraldehyde-concentration,2 mmol·L^-1,amount of AR(41μg·μL^-1),40μL.2.Different concentration of captopril,lisinopril,benazepril,Lei enalapril were all inhibited the activity of AR compared to negative groups and show a significant dose-effect relationship(P＜0.05).3.The activity of myocardial AR were decreased by captopril(0.032±0.012 AU) and significantly decreased by lisinopril(0.042±0.010 AU,P＜0.05) in SHR.The change trendancy of AR activity in in each group was in a linear relationship with the concentration of AngⅡ(R=0.695,P=0.004).Conclusion:established the method of optimize the determination of aldose reductase activity.ACEI such as captopril,lisinopril,benazepril,Lei enalapril on aldose reductase have inhibitory action.