摘要：Previous reports have shown that ginseng saponins, the active ingredients of Panax ginseng , induce relaxation of hormone- or high K+-induced blood vessel contraction. We recently demonstrated that 20( R )- and 20( S )-ginsenoside Rg3 epimers regulate ion channel activities in a stereospecific manner. Here, we examined whether ginsenoside Rg3 epimers also exhibit differential effects on swine coronary artery contractions induced by high K+ or 5-HT. We found that treatment with 20( S )- but not 20( R )-ginsenoside Rg3 caused a potent concentration-dependent, endothelium-independent relaxation of coronary artery contraction induced by 25 m M KCl. However, treatment with both 20( S )- and 20( R )-ginsenoside Rg3 induced a significant, concentration-dependent relaxation of 3 μ M 5-HT-induced coronary artery contractions in intact samples, while only 20( S )-ginsenoside Rg3 inhibited coronary artery contraction in endothelium-denuded arteries. 20( S )- but not 20( R )-ginsenoside Rg3 inhibited L -type Ca2+ channel currents in a dose- and voltage-dependent manner. These results indicate that 20( S )- and 20( R )-ginsenoside Rg3 epimers might exhibit stereospecific relaxation effects on swine coronary artery contractions caused by high K+ and 5-HT receptor activation.
