| Objective: To screen the vasodilative fractions from Hebeibalmy chrysanthemum and analysis the possible mechanism.Methods: Observing the effects of several extracts ofHebei balmy chrysanthemum in the rabbit isolated thoracicaorta rings pre-contracted phenylephrine (PE, 1μmol·L-1), andanalysing the effects of the active fractions on thevasoconstriction induced by high K+, PE, extracellular Ca2+ andintracellular Ca2+.Results: The fractions of extract residuum, ethyl acetateextract (EtOAc-extract) at 0.3～30g·L-1 did not produce anyeffects on the resting tension in the rabbit isolated thoracic aorta(P＞0.05); petroleum ether extract (petro-extract), n-butanolextract, water extract and 70% alcohol extract at 30g·L-1produced vasoconstriction (P＜0.01). In the rabbit isolatedthoracic aorta pre-contracted with PE, 70% alcohol extract,n-butanol extract, ethyl acetate extract, extract residuum andwater extract at 0.3～30g·L-1 vasodilated the thoracic aortaconcentration-dependently. The potency order of the vasodilation induced by these fractions was extract residuum, n-butanolextract, 70% alcohol extract, water extract, ethyl acetate extract. At 30g·L-1 70% alcohol extract, n-butanol extract, ethyl acetateextract, extract residuum and water extract producedvasodilation by 67.32%, 76.67%, 53.85%, 82.22%, 54.67%.Dichlormethane (CH2Cl2) extract residuum did not produceany effects on the resting tension in the rabbit isolated thoracicaorta (P＞0.05); 40% alcohol extract at 30g·L-1 produced thevasoconstriction (P＜0.01); 40% alcohol extract and CH2Cl2extract residuum at 30g·L-1 induced vasodilatation by 37.79%,44.88%.The fractions of eluate 1, eluate 2, eluate 4 at 1.5g·L-1produced the vasodilation in the rabbit isolated thoracic aortapre-contracted with PE (P＜0.01), and eluate 1, eluate 2 andeluate 4 at 1.5g·L-1 induced vasodilatation by 26.52%, 28.64%,26.82%.The 60% alcohol eluate at 0.03～3g·L-1 and at0.038～11.4g·L-1 water eluate did not produce any effects on theresting tension in the rabbit isolated thoracic aorta (P＞0.05). Inthe rabbit isolated thoracic aorta pre-contracted with PE, 60%alcohol eluate at 1g·L-1 and 3g·L-1 vasodilated the arteryconcentration-dependently (P＜0.01), water eluate at 3.8g·L-1and 11.4g·L-1 produced the similar effects (P＜0.01); 3g·L-1 60%alcohol eluate and 11.4g·L-1 water eluate vasodilated the arteryby 56.51% and 63.66%.KCl (15～75mmol·L-1) induced the concentration dependentvasoconstrictive response, and the concentration-response curvefor KCl was shifted to the right with a decrease in the maximum response by 60% alcohol eluate 3g·L-1 in the rabbit isolatedthoracic aorta. In the presence of 3.8g·L-1 and 11.4g·L-1 watereluate, however, the concentration response curve for KCl wasshifted to the left.PE (0.01～30μmol·L-1) induced the concentration dependentvasoconstrictive response, and the concentration response curvefor PE was shifted to the right and with a decrease in themaximum response by 60% alcohol eluate (3g·L-1). In thepresence of 1.14g·L-1 and 11.4g·L-1 water eluate the concentrateon-response curve for PE was shifted to the left.The fractions of 60% alcohol eluate at 0.03g·L-1 and0.3g·L-1 and water eluate at 1.14g·L-1 did not inhibit the extracellular Ca2+-dependent vasoconstriction and the intracellularCa2+-dependent vasoconstriction in the rabbit isolated aorta (P＞0.05). At 3g·L-1 60% alcohol eluate significantly enhanced theintracellular Ca2+-dependent vasoconstriction of the thoracicaorta induced by NA, however, it inhibited the extracellularCa2+-dependent vasoconstriction, and inhibited the totalvasoconstriction (the sum of the extracellular and intracellularCa2+-dependent vasoconstriction) (P＜0.01). Water eluate significantly at 3.8g·L-1 and 11.4g·L-1 enhanced the intracellularCa2+-dependent vasoconstriction of the thoracic aorta, however,inhibited the extracellular Ca2+-dependent vasoconstriction, andwater eluate at 11.4g·L-1 inhibited the total Ca2+-dependentvasoconstriction (P＜0.05).Water eluate at 11.4g·L-1 produced a vasodilation in the rabbit isolated thoracic aorta pre-contracted with PE (P＜0.01)or KCl (P＜0.05), however, in the artery pre-incubated with11.4g·L-1 water eluate for 20min did not alter thevasoconstrictive responses to PE or KCl were not changedsignificantly in comparison with the same concentrations of PEor KCl using as pre-constrictive agents.Conclusion:1 Water eluate and 60% alcohol eluate are the activefractions of Hebei balmy chrysanthemum with vasodilativeeffects in the rabbit isolated thoracic aorta.2 The mechanism of the vasodilation in the rabbit isolatedthoracic aorta induced by 60% alcohol eluate might be related toits blocking effects on a1 adrenoceptors and voltage-dependentCa2+ channels, however, that by water eluate is different from60% alcohol eluate. |
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