Vasodilation Effect of Extract of Jasminum samba / 医药导报

ABSTRACT

Objective To observe the vasodilation effect of extract of Jasminum samba (EJs), a kind of traditional Chinese medicine, on ex vivo rat thoracic aortic rings, and to investigate its mechanism. Methods On ex vivo aortic ring perfusion device, influence of EJs on contraction of the aorta induced by phenylephrine (PE) or potassium chloride (KCl) was observed. Influence of N-nitro-L-arginine-methylester ( L-NAME ), barium chloride ( BaCl2 ), glibenclamide ( Gli ) on vasodilating effect of EJs (0. 5, 1, 2, 4, 8 g·L-1 ) was detected. Effect of EJs on the contraction of calcium chloride (CaCl2 ) and PE in Ca2+-free medium was detected. [ Ca2+ ] i in vascular smooth muscle cells was determined by using laser scanning confocal microscope (LSCM). Results In blood vessels with intact endothelium, EJs concentration-dependently decreased PE- or KCl-induced vasoconstriction, the maximum dilating effect being (105. 0±3. 2)% and (78. 0±6. 5)% , respectively; L-NAME affected the vasodilatory effect of EJs on thoracic aorta rings ( P<0. 01), the maximum dilatory effect being (58. 0 ± 6. 9)% . BaCl2 and Gli had significant influence on vasodilation of EJs, and the contraction was obviously attenuated (P<0. 01), the maximum dilatory effect being (37. 0±5. 2)% and (78. 0±10. 0)% , respectively. EJs significantly inhibited contracting effect of PE on thoracic aorta rings in Ca2+-free medium (P<0. 01). The maximum contraction effect was (70. 0±6. 3)% . EJs inhibited CaCl2-induced vasoconstriction (0. 5-8 mmol·L-1 ), and vasoconstriction was decreased by (65. 0±3. 2)% . LSCM recorded that Fmax / F0 of 4 and 8 g·L-1 EJs was (2. 0±0. 2) and (1. 5±0. 2), respectively. Conclusion EJs exerted a dose-dependent vasodilating effect on rat isolated aorta rings. The mechanism might be related to promoting NO release, activating K+channels and decreasing the concentration of cytoplasmic Ca2+.