Vasorelaxation effect of oxysophoridine on isolated thoracicc aorta rings of rats.

Oxysophoridine (OSR) is a main active alkaloid extracted from Sophora alopecuroides, which is a traditional Chinese herbal medicine that has been used widely. In this study, we used thoracic aorta rings isolated from Sprague-Dawley rats to explore the vasodilative activity of OSR and its potential mechanisms. The isolated rat thoracic aorta rings were used to observe the effects of different concentrations of OSR (0.4-2.0 g·L-1) on the resting normal rings and the phenylephrine precontracted endothelium-intact or endothelium-denudedisolated thoracic aorta rings, respectively. The interactions among OSR and barium chloride (BaCl2), tetraethylamine, 4-aminopyridine, glibenclamide (Gli), L-nitroarginine methyl ester (L-NAME), and cyclooxygenase (COX) inhibitor indomethacin (INDO) were evaluated. The experimental results show that OSR had no effect on the tension of resting vascular rings, but the vasodilating effect could be confirmed in a concentration-dependent manner on both endothelium-intact and endothelium-denuded vascular rings. This vasodilation effect of OSR on thoracic aorta vascular rings could be inhibited significantly by potassium channel blockers glibenclamide (Gli, 10 µmol·L-1) and 4-aminopyridine (4-AP, 5 mmol·L-1). In addition, vasodilatory effects of OSR were not inhibited in the presence of potassium channel blockers barium chloride (BaCl2, 1 mmol·L-1) and tetraethylamine (TEA, 10 mmol·L-1), nitric oxide synthase inhibitor (L-NAME, 0.1 mmol·L-1) and COX inhibitor (INDO, 10 µmol·L-1). In conclusion, the vasodilatory effects of OSR on thoracic aorta rings is associated with KV and KATP.

Vasodilatory Effects of Aloperine in Rat Aorta and Its Possible Mechanisms.

The aim of this study was to investigate the vasodilatory effects of aloperine, one of main alkaloid was extracted from Sophora alopecuroides, on rat isolated thoracic aortic rings and its possible mechanisms. The isolated aortic arteries from normotensive Sprague Dawley rats were precontracted with phenylephrine (1 × 10⁻6 M) or KCl (60 mM). Then, aloperine (3.44 × 10⁻³ ­ 17.21 × 10⁻³ M) was added cumulatively and the tension curves was observed and recorded. The changes in tension in both endothelium-intact and endothelium-denuded aortic rings were also recorded. Afterwards, the interaction between aloperine with NG-nitro-L-arginine methylester (0.1 mM), indomethacin (1 × 10⁻³ mM), tetraethylammonium (10 mM), 4-aminopyridine (5 mM), BaCl2 (1 mM) and glibenclamide (0.01 mM) was evaluated. In this study, aloperine caused concentration-dependent relaxations in aortic rings precontracted with phenylephrine, but this effect was not observed in KCl-pretreated rings. Removal of endothelium showed no influence on vasodilatory effects of aloperine. In addition, preincubation with NG-nitro-L-arginine methylester and indomethacin did not inhibit the vasodilatory effects of aloperine, suggesting that the vasodilative action is endothelium-independent. Relaxant responses to aloperine were inhibited by tetraethylammonium and 4-aminopyridine. However, the vasorelaxant effect of aloperine was also not influenced by the preincubation with BaCl2 and glibenclamide. These findings suggest that aloperine-induced vasorelaxation effects are mainly due to the operations of voltage-operated potassium channels and ATP-sensitive potassium channels.