OBJECTIVETo study the vasodilation effects of the Total alkali Sophora alopecuroids L (TASa) on rabbit thoracic aortic rings in vitro and the possible mechanisms.

METHODRabbit aortic rings were isolated and precontracted with noradrenaline (NA) and then were divided into six groups including control group, TASa group, TASa + 1 x 10(-5) mol x L(-1) indomethacin (Indo), TASa + 1 x 10(-5) mol x L(-1) propranolol (Prop), TASa + 1 x 10(-10 mol x L(-1) N(omega)-nitro-L-arginine (L-NNA), TASa + removal of endothelium. The vasodilation effects of TASa were investigated. In addition, the thoracic aortic rings were pre-treated with TASa (40 mg x L(-1)) and then the thoracic aortic rings were treated with cumulative NA (110(-8)-110(-5) mol x L(-1)), KCl (6.3-100 mmol x L(-1)) or CaCl2 (110(-5)-110(-2) mol x L(-1)). The dose response curves of aortic rings were recorded.

RESULTTASa can relax isolated rabbit aorta and has an obvious concentration-dependent relaxation (r = 0.94, P < 0.01). The relaxant effect of TASa was no significant reducing by removal of endothelium and by treatment with L-NNA, Indo or Prop. In addition, TASa can decrease the dose response curves of aortic rings to NA, KCl or CaCl2.

CONCLUSIONThe vasodilation effects of TASa are related to not only inhibition of intracellular calcium release, but also reduction to calcium flow to the interior of the cell with blockage of calcium channels.