用豚鼠离体乳头肌的收缩力相对增强百分率为正性肌力作用的指标，研究了黄芪注射液及其各分离部分的活性，证明中性部分为有效部位；其正性肌力作用呈浓度依赖关系。并用放射配基受体结合分析法，证明其作用不是通过β-肾上腺素受体，也不依赖于儿茶酚胺的释放。活性部分的成分，通过柱层析分离出单体，并经波谱数据分析和标准样品直接对照，证明该单体为黄芪甙Ⅳ。<span style="color: rgb(51, 51, 51); font-family: 宋体; font-size: 12pt;" ar-sa;"="" zh-cn;="" en-us;="" 0pt;="" arial;="" yahei";="" "microsoft="" microsoft="">

Astragulus membranaceus (Fisch. ) Bge. (Leguminosae) is widely used in Chinese traditional medicine as an antiperspirant, a diuretic or a tonic. By bioactivity-guided fractionating, a positive inotropic constituent has been characterized from the neutral portion of Huangqi injection, using modified Robert’s method as a guide. Its activity correlated well with the dosage of neutral portion and the result of radio- complement- receptor combination analysis suggests that the positive inotropic effect of Huangqi injection neither mediated through β-adrenaline receptor nor depended on the releasing of catechoamine. The constituents of Huangqi injection neutral portion have been isolated and identified by analysis of their spectra data and confirmed by direct comparison with authentic samples. It may be concluded that astragaloside Ⅳ from Huangqi injection neutral portion is the active constituent with positive inotropic activity.