The effect of total saponins from Panax Ginseng C.A. Meyer on the intracellular signalling system in Ehrlich ascites tumor cells

The mechanisms of action of total saponins from Panax Ginseng C.A. Meyer on the elements of intracellular signalling system in Ehrlich ascites tumor cells were studied. The action of total saponins was compared with the effect of ATP, a classical activator of these cells. Saponins at concentrations of 10^-6-10^-3% increased [Ca²⁺](i), mobilized Ca²⁺ ions from the endoplasmic reticulum (ER) and activated the influx of Ca²⁺ to cells. Like ATP, saponins activated the Na⁺/H⁺ exchange and Ca²⁺-dependent K⁺ channels. Of all the parameters, only the activation of Ca²⁺ influx in cell is directly affected by saponins. The changes in other parameters are connected with nonspecific activation of purinoreceptors. The analysis of the kinetic data suggests that, as distinct from ATP-dependent activation of purinoreceptor, saponins first activate the Ca²⁺ influx to cells and only then induce the mobilization of Ca²⁺ from ER.