Effect of the total saponins of Aralia elata (Miq) Seem on cardiac contractile function and intracellular calcium cycling regulation

Ethnopharmacological relevance

Total saponins of Aralia elata (Miq) Seem (AS) from the Chinese traditional herb Longya Aralia chinensis L. can improve cardiac function, although the active mechanism remains poorly understood. The present study aimed to determine the direct effect of AS on cardiac function in dogs and the effects on Ca²⁺ transient and contractions in isolated rat cardiomyocytes.

Material and Methods

In anesthetized dogs, hemodynamic indexes and myocardial oxygen consumption were determined before and after AS was administered. In isolated adult rat cardiomyocytes, contractile and intracellular Ca²⁺ properties were determined simultaneously in real time by using an IonOptix MyoCam system.

Results

Our results showed that AS directly induced a positive inotropic effect and improved coronary blood flow and energy metabolism, indicating that AS induced a beneficial effect to treat myocardial ischemia/reperfusion injury. Moreover, AS increased sarcomere shortening, maximal velocity of shortening/relengthening (±dL/dt), amplitude of Ca²⁺]_i transients and SERCA activity in a concentration-dependent manner. PKCε was also activated after the cells were treated with AS.

Conclusion

These findings revealed the positive inotropic effect of AS on canine myocardium and isolated rat cardiomyocytes. This effect was possibly associated with an increase in amplitude of the Ca²⁺]_i transient and PKCε-dependent signaling pathway.