Effects of astragaloside IV on myocardial calcium transport and cardiac function in ischemic rats

To explore the effects of astragaloside IV (XGA) on myocardial calcium transport and cardiac function in ischemic rats.

Eighty-four Wistar rats were divided into three groups: control group (n=12); ischemic group (n=12) was given isoprenaline injection sc at a dose of 30 mg/kg; and XGA group (n=60) was given XGA after isoprenaline administration. The changes of the parameters of hemodynamics, cardiac function, and intra- and extracellular calcium concentration of the myocardial cells were determined. The dose- and time-effect relationship of XGA on myocardial calcium transport and cardiac function were observed.

After XGA administration, there was significant improvement in cardiac function and hemodynamics in ischemic rats. The cardiac output, heart rate, stroke volume, mean aortic pressure, systolic aortic pressure, the stroke work of left ventricule, the right and left ventricle systolic pressure, and +dp/dt of the right ventricle of ischemic rats gradually recovered to the level of the control group with increasing the dose of XGA and prolongation of the action of XGA. The ionized calcium of the myocardium and the total amount of calcium of the myocardial tissue decreased markedly compared to those in ischemic group, and the activity of calcium pump of erythrocyte membrane increased significantly in comparison to that of ischemic group, but their changes had no trend of increase with increasing dose of the XGA. However, there was a gradual decrease of the ionized calcium of the myocardium with the prolongation of acting time of XGA.

XGA improves the cardiac function in ischemic rats, and the reduction of excessive accumulation of intracellular calcium within myocardial cells plays an important role.