Protective Effect Of AstragalusⅣ On Isoprenaline-induced Cardiac Hypertrophy

ObjectiveThe aims of this study were to detemine whether Astragalus IV(As IV) can attenuate cardiac hypertrophy induced by isoproterenol(Iso) in cultured neonatal rat cardiac myocytes in vitro and in SD rats in vivo .MethodsIn vivo experiments cardiac hypertrophy in SD rats was induced by subcutaneous injection of isoproterenol at interval of 24. Sixty SD rats were randomized into 5 groups, the normal control group, the model group, and the As IV 20,40,60 mg/kg/d groups. The model and As IV groups was induced by subcutaneous injection of Iso at the dose of 5mg/kg/d. The As IV was given at the second day of Iso administration. The cardiac hypertrophy was evaluated by HW/BW (heart weight/body weight) and LVW/BW(left ventricular weight/body weight). Activity of ATPase was determined in left ventricular tissues by ATPase Assay Kit. The content of FFA was measured and myocardial pathological examination was performed.In vitro experiments As IV was 3³0μmol·L^-1 added to cultured myocardial cells 30 min prior to incubation with Iso 10μmol·L^-1 for 48h. The total protein was measured by the Bradford Protein Assay Kit. The size was assayed by computer photogra analysis. The cell viability was assessed by MTT assay. [Ca²⁺]i transient was measured by Till image system by cell-loading Fura-2/AM.ResultsIn vivo experiments compared with normal control group, the increase of HW/BW ratio, LVW/BW ratio and FFA content were observed after Iso treatment. And the decrease of Na⁺-K⁺-ATPase and Ca²⁺-ATPase activity were 55.29%, 39.89% (P<0.01). The AsIV 60mg/kg/d can restored the ATPase activity and reduced the content of FFA and the ratio of HW/BW and LVW/BW.In vitro experiments compared with the normal control group, the increase of the total protein content, cardiomyocytes size, [Ca²⁺]i transient and the decrease of cell viability in cultured myocardial cells were observed incubated with Iso for 48h. The survival rate of myocardial cells was decreased of 48.1% in Iso-treated group(P<0.01). Pretreated with AsIV 30μmol·L^-1 can protect aganist the increasing of protent content and even recover to the level of normal control group.ConclusionsIt is demonstrates that AsIV can attenuate cardiac hypertrophy through inhibiting [Ca²⁺] and changing of energy metabolic pathway.