In order to investigate the effects of isoliensinine(IL) on cardiovascular function and left ventricular hypertrophy (LVH), a rat model of LVH was established by destroying spinal cord and partial ligation of abdominal aorta. The action of IL (10 or 20 mg/kg every day for 6 weeks) on contractile force (Fc), pacemaker frequency and Ca 2+ dose response curve were examined in isolated left or right atria. Its effect on systolic arterial pressure (SAP) and diastolic arterial pressure (DAP) were observed in pithed rat pretreated with PE. The hemodynamics, whole heart weight (WHW)/body weight (BW), left ventricular weight (LVW)/body weight (BW), and hydroxyproline (Hyp) content were measured. It was found that IL produced a dose dependent negative inotropic with IC 50 value of 39.8 μmol/L and a chronotropic effect, shifted Ca 2+ dose response curve to the right, decrease the maximal response with the pD 2 ' value of 4.66. IL also abolished the increasing effect of PE on SAP and DAP. In the rats with LVH, IL decreased SAP, LVSP, LVEDP, and increased -dp/dtmax. Moreover, it reduced the WHW/BW, LVW/BW, and Hyp content ( P <0 05 or P <0 01). It was concluded that IL blocked Ca 2+ influx and antagonized the function of α 1 adrenergic receptor, which might responsible for its protecting heart from LVH.