| Objectives: To explore the influence and mechanism of recombinant human brain natriuretic peptide(rhBNP)and furosemide on diuretic effect in rats with heart failure with reduced ejection fraction(HFrEF)by detecting the expression of renal aquaporin-2(AQP2)and the concentration of AQP2 in urine,and to provide a theoretical basis for the clinical application of rhBNP in improving diuretic effect of furosemide in patients with HFrEF.Methods: We established the model of HFrEF after acute myocardial infarction by ligating the left anterior descending of male Wistar rats.Four weeks after the operation,the survival rats were detected by ultrasound(Ejection Fraction,EF<55%),suggesting that the model was successfully established.The successfully established model rats were randomly divided into the model group,the rhBNP group,the furosemide group,and the rhBNP+furosemide group.Another sham-operation group was set up.The blood and urine samples were collected at 4 weeks after intervention,and the24-hour liquid intake and output of the rats were also recorded at 2 and 4weeks after intervention.Plasma detection: Angiotensin II(AngII),Aldosterone(ALD),Arginine Vasopressin(AVP),and N-terminal pro brain natriuretic peptide(NT-pro BNP).Urine detection: concentration of AQP2 and creatinine.The heart function of rats was evaluated by ultrasonic examination at 4 weeks after intervention.Meanwhile,the expression of AQP2 in rats’ kidney was detected by immunohistochemistry(ICH),western blot(WB)and Real-time quantitative Polymerase Chain Reaction(RT-PCR).Results:1.Concentration of AngII,ALD,AVP and NT-proBNP in rats’ plasma: 4weeks after the intervention,the rhBNP group and the rhBNP+furosemidegroup were both lower than that of the model group and the furosemide group(P < 0.05),but were higher than that of the sham-operation group(P < 0.05).For the first three indicators : the furosemide group was higher than that of the model group(P <0.05);no statistical difference was found between the rhBNP group and the rhBNP+furosemide group(P > 0.05).For the last indicator : no statistical differences were found between the following comparisons: the rhBNP group and the rhBNP+furosemide group,the furosemide group and the model group(P>0.05).2.Excretion rate of AQP2(urine AQP2 concentration/creatinine)in the urine of rats: 4 weeks after intervention,the rh BNP group and the rhBNP+furosemide group were lower than that of the model group and the furosemide group(P<0.05),but were higher than the sham-operation group(P< 0.05);the furosemide group was higher than the model group(P < 0.05);no significant difference was found between the rhBNP group and the rhBNP+furosemide group(P > 0.05).3.Difference of the 24-hour intake and output in rats: 2 weeks after intervention,the furosemide group and the rh BNP+furosemide group were higher than that of the rhBNP group(P < 0.05).No significant difference was found between the furosemide group and the rhBNP+furosemide group(P >0.05).The first three groups were higher than the sham-operation group and the model group(P < 0.05),the sham-operation group was higher than the model group,and the difference was statistically significant(P < 0.05).4weeks after intervention,the rhBNP+furosemide group was higher than that of the rhBNP group and the furosemide group(P < 0.05);the furosemide group was higher than the rh BNP group(P < 0.05).Meanwhile,the first three groups were higher than the sham-operation group and the model group(P < 0.05).At the same time,the sham-operation group was higher than the model group,and the difference was statistically significant(P < 0.05).4.Ultrasound results of rats at 4 weeks after intervention: Comparison of left ventricular end diastolic diameter(LVEDD)and left ventricular end systolic diameter(LVESD): the rhBNP group and the rhBNP+furosemidegroup were lower than that of the model group and the furosemide group(P <0.05),but were higher than the sham-operation group(P<0.05).However,no statistical differences were found between the following comparisons: the rhBNP group and the rhBNP+furosemide group,the furosemide group and the model group(P>0.05).Comparison of ejection fraction(EF)and shortening fraction(FS): the rhBNP group and the rhBNP+furosemide group were higher than that of the model group and the furosemide group(P<0.05),but were lower than that of the sham-operation group(P<0.05).However,no statistical significant differences were found between the following comparisons: the rhBNP group and the rhBNP+furosemide group,the furosemide group and the model group(P > 0.05).5.The expression of AQP2 protein or mRNA levels in rats’ kidney at 4weeks after intervention: the rhBNP group and the rhBNP+furosemide group were lower than that of the model group and the furosemide group(P < 0.05),but were higher than the sham-operation group(P < 0.05).The furosemide group was higher than the model group(P < 0.05);no significant difference was found between the rhBNP group and the rhBNP+furosemide group(P >0.05).Conclusion: The combination of rhBNP and furosemide was used in rats with HFrEF.rhBNP could antagonize the over activation of the neuroendocrine system and reduce the excretion rate of urine AQP2 as well as the expression of AQP2,decrease the renal tubular reabsorption of sodium and water,enhance the diuretic effect of furosemide,and improve the retention of water and sodium and heart function. |
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