Effects And Mechanism Of Astragalus Polysaccharides On Endothelial Function In Myocardial Hypertrophy Rats Induced By Isoproterenol

ObjectiveTo investigate the protective effect of Astragalus polysaccharide（APS）on endothelial in cardiac hypertrophy rats induced by isoproterenol（ISO）.MethodsIn vivo,ISO 10mg﹒kg-1﹒d-1 was given by intraperitoneal injection to set a myocardial hypertrophy model.40 SD rats were randomly divided into four groups（n=10）: control group;ISO model group;ISO + APS 400 mg﹒kg-1﹒d-1;ISO + APS 800 mg﹒kg-1﹒d-1.Each group administered orally two weeks in a row,and was given an ISO 2 weeks by intraperitoneal injection from the second day,the control group received an equal volume of normal saline.After the last administration fasting 12 h,blood and heart were taken under anesthesia.The circulating endothelial cells（CEC）were isolated and counted.The vascular function was also assessed with isolated aortic rings.The levels of TNF-α,IL-6 and c GMP were measured with ELISA kits.The heart mass index（HMI）,left ventricular mass index（LVMI）were also observed;The level of superoxide anion in aorta tissue was detected by DHE staining;p65,IκBα and Cu /Zn-SOD protein expression of Vascular tissue was detected by Western blot.In vitro,the HUVECs were preincubated with different concentrations of APS（0.1μg/ml,1μg/ml,10μg/ml）for 1h and subsequently stimulted with 400μmol/L H₂O₂ for 24 h.The cell viability was detected by MTT assay;the apoptosis was evaluated by flow cytometry;the mitochondrial membrane potential（?Ψm）of HUVECs was assessed with fluorescent dye rhodamine123;The levels of cGMP was measured with ELISA kits;the expression of eNOS and Cu/Zn-SOD were assessed by Western blot.ResultsCombination with APS could significantly ameliorates the endothelial dysfunction while attenuates cardiac hypertrophy induced by ISO.Compared with the ISO model group in vivo,we found that administration with APS could attenuate the increase in number of circulating endothelial cell（CEC）.APS also decreases the superoxide anion generation and the protein expression of p65 and the levels of TNF-α and IL-6;while increases the cGMP levels,an activity marker for nitric oxide（NO）in aortas.In addition,APS improves the relaxation dysfunction in isolated aortic rings and increases the protein expression of IκBα and Cu/Zn-SOD in aortas.In vitro,after treated with 400μmol/L H₂O₂ for 24 h the cell viability were decreased and apoptosis rate were increased compared to control group.However,pretreatment with APS（0.1-10μg/m L）for 1h could significantly attenuate the increasing of apoptosis rate induced by H₂O₂ in HUVECs compared to model group.We also found that APS could increase the protein expression of eNOS and Cu/Zn-SOD,elevate intracellular cGMP levels,an activity marker for nitric oxide,and restore the mitochondrial membrane potential compared with cells of H₂O₂ model group.ConclusionsAPS had a protective effect against endothelial dysfunction in hypertrophic rats induced by ISO.The underlining mechanisms may be contributed to the anti-inflammatory effects and the improvement of the imbalance between reactive oxygen species（ROS）and NO.