Hypotensive effects of lithospermic acid B isolated from the extract of Salviae miltiorrhizae Radix in the rat

Abstract

1. 1. The in vivo and in vitro effects of lithospermic acid B (LSA-B), which was extracted from Salviae miltiorrhizae Radix, on vascular relaxation responses were examined in rats. 2. 2. Intravenous injection of LSA-B (10-30 mg/kg) decreased the blood pressure in a dose-dependent manner. 3. 3. In perfused mesenteric arterial bed precontracted with methoxamine (10 −5 M), LSA-B (10 −5–10 −3 M) produced a concentration-dependent relaxation. 4. 4. Vasodilator response of the mesentery in response to LSA-B was reversed by 10 −4 M N G-monomethyl- l-arginine ( l-NMMA). 5. 5. The inhibition of vasodilation by l-NMMA was reversed by l-arginine (3 × 10 −4 M). 6. 6. These results suggest that LSA-B-induced hypotensive effect may be due to the endothelium-dependent vasodilation of resistance artery such as mesenteric arterial bed.