Ginsenoside-Rd, a new voltage-independent Ca2+ entry blocker, reverses basilar hypertrophic remodeling in stroke-prone renovascular hypertensive rats

The total saponins of Panax notoginseng have been clinically used for the treatment of cardiovascular diseases and stroke in China. Our recent study has identified ginsenoside-Rd, a purified component of total saponins of P. notoginseng, as an inhibitor to remarkably inhibit voltage-independent Ca2+ entry. We deduced a hypothesis that the inhibition of voltage-independent Ca2+ entry might contribute to its cerebrovascular benefits. Ginsenoside-Rd was administered to two-kidney, two-clip (2k2c) stroke-prone hypertensive rats to examine its effects on blood pressure, cerebrovascular remodeling and Ca2+ entry in freshly isolated basilar arterial vascular smooth muscle cells (BAVSMCs). Its effects on endothelin-1 induced Ca2+ entry and cellular proliferation were assessed in cultured BAVSMCs. The results showed that, in vivo, ginsenoside-Rd treatment attenuated basilar hypertrophic inward remodeling in 2k2c hypertensive rats without affecting systemic blood pressure.During the development of hypertension, there were time-dependent increases in receptor-operated Ca2+ channel (ROCC)-, store-operated Ca2+ channel (SOCC)- and voltage dependent Ca2+ channel (VDCC)-mediated Ca2+ entries in freshly isolated BAVSMCs. Ginsenoside-Rd reversed the increase in SOCC- or ROCC- but not VDCC-mediated Ca2+ entry. In vitro, ginsenoside-Rd concentration-dependently inhibited endothelin-1 induced BAVSMC proliferation and Mn2+ quenching rate within the same concentration range as required for inhibition of increased SOCC- or ROCC-mediated Ca2+ entries during hypertension. These results provide in vivo evidence showing attenuation of hypertensive cerebrovascular remodeling after ginsenoside-Rd treatment. The underlying mechanism might be associated with inhibitory effects of ginsenoside-Rd on voltage-independent Ca2+ entry and BAVSMC proliferation, but not with VDCC-mediated Ca2+ entry.