Relaxant effects of ethanol extract from Rhodiola crenulata in isolated rat thoracic aortic rings / 国际中医中药杂志

ABSTRACT

Objective To investigate the relaxant effects of ethanol extract fromRhodiola crenulata (Hook.f.et Thoms.) H.Ohba in isolated rat thoracic aorta and its possible mechanisms.MethodsThe thoracic aortas from male Sprague-Dawley rats were isolated and cut into 3- to 4-mm-wide transverse rings, and the tension in endothelium-intact or endothelium-denuded aortic rings was recorded. The relaxant effects of ethanol extract fromRhodiola crenulata in various concentrations (100, 300, 500, 700, 900, and 1 100 mg/L) in aortic rings precontracted with phenylephrine (1 μmol/L) were observed. The effects of pretreatment with soluble guanylyl cyclase inhibitor ODQ (10 μmol/L) on the relaxant effects of ethanol extract fromRhodiola crenulata were observed. The effects of ethanol extract fromRhodiola crenulataon calcium-induced contractions in calcium-free high-potassium medium and phenylephrine-induced contractions in calcium-free medium were also observed.ResultsEthanol extract fromRhodiola crenulatashowed a concentration-dependent relaxation in aortic rings precontracted with phenylephrine. The maximal relaxations of ethanol extract fromRhodiola crenulataln endothelium-intact or endothelium-denuded aortic rings were 57.4% ± 21.81% and 60.51% ± 0.34%, respectively, with a half-maximal effective concentration of 1 062.88 mg/L. The relaxant effects of ethanol extract fromRhodiola crenulatawere not statistically inhibited by pretreatment with ODQ (P>0.05). Contractions of aortic rings resulted from phenylephrine-induced Ca2+ release from intracellular stores in calcium-free medium or high potassium-induced influx of Ca2+ in calcium-free high-potassium medium were significantly inhibited by ethanol extract fromRhodiola crenulata(allP<0.05).ConclusionEthanol extract fromRhodiola crenulatahas a concentration-dependent vasorelaxation, its mechanisms may be involved in blocking extracellular Ca2+ influx and intracellular Ca2+ release.