石斛对大鼠胸主动脉环的舒张作用

目的 :观察石斛的血管效应并探讨其作用机制。方法 :采用大鼠离体胸主动脉环灌流 ,记录张力变化。结果 :石斛 (0.01～3g·L^{- 1})剂量依赖性地舒张苯肾上腺素 (PE,3×10^-7mol·L^-1)预收缩的内皮完整或去内皮的大鼠胸主动脉环 ;在高浓度氯化钾 (6×10^-2 mol·L^-1)预收缩的去内皮动脉环 ,石斛剂量依赖性地舒张血管 ;在无钙液中 ,石斛抑制PE(10-6mol·L^-1)引起的去内皮主动脉环的短暂收缩 ;K⁺ 通道阻断剂四乙胺 (TEA ,5×10-3mol·L^-1)预处理去内皮的动脉环 ,可部分抑制石斛的舒血管作用。结论 :石斛的血管舒张作用是非内皮依赖性的 ,其舒血管机制可能与其减少Ca²⁺ 经电压依赖性钙通道和受体操纵性钙通道流入血管平滑肌细胞 ,以及抑制内质网内Ca²⁺ 释放有关 ;TEA敏感性K⁺ 通道的激活部分参与了石斛的舒血管作用。     

木犀草素对大鼠主动脉的舒张作用及相关机制研究

 目的观察木犀草素的舒血管作用并探讨其作用机制。方法大鼠胸主动脉环张力测定法。结果在内皮完整及去内皮血管上,木犀草素均浓度(4.5～36 μmol·L^-1)依赖性地降低苯肾上腺素(PE)预收缩血管的张力,拮抗高钾引起的血管收缩;木犀草素使PE收缩曲线非平行右移,且使最大张力减小;L-NAME,propranolol对木犀草素的舒血管作用无显著影响;钾通道阻断剂TEA,4-AP,BaCl₂,5-HD均能显著减弱木犀草素的血管舒张作用;木犀草素可以显著地对抗无钙、无钾、无钙环境下渐复钙后由PE引起的血管收缩。结论木犀草素对血管的舒张作用表现为非内皮依赖性,其舒张作用与其直接抑制电压依从性钙通道、受体操纵性钙通道、细胞内钙释放,以及激活钾通道有关,而与α,β受体无关。     

芦丁对离体大鼠主动脉环的舒张作用及相关机制

 目的研究芦丁对离体大鼠胸主动脉环收缩张力的作用及其可能作用途径。方法采用累积加药法,检测芦丁对去氧肾上腺素(PE)预收缩的胸主动脉环收缩张力的影响,研究芦丁对血管张力的影响及其机制。结果芦丁(10～160μmol·L^-1)对内皮完整的离体大鼠胸主动脉环具有浓度依赖性舒张作用。芦丁对内皮完整的胸主动脉环的最大舒张反应(R_max)为(44.28±7.48)%。用一氧化氮合酶抑制剂左旋硝基精氨酸甲酯(L-NAME,0.1 mmol·L^-1)、鸟苷酸环化酶抑制剂亚甲蓝(10μmol·L^-1)和环氧合酶抑制剂吲哚美辛(10 mmol·L^-1)预处理后,均可明显减弱芦丁诱导的舒张血管作用;用β受体阻断剂普萘洛尔(10μmol·L^-1)预处理后,芦丁的血管舒张作用不能被阻断。结论芦丁可能是通过NO-鸟苷酸环化酶途径和前列腺素介导机制产生内皮依赖性的血管舒张作用。     

白藜芦醇对大鼠离体胸主动脉环的舒张作用

目的:观察白藜芦醇(resveratrol,RVL)对大鼠离体胸主动脉血管的舒张作用并探讨其机制。方法:采用离体血管环灌流方法,观察RVL在含Ca²⁺或无Ca²⁺ Krebs液孵育条件下对去甲肾上腺素(NA)引起的血管平滑肌收缩的影响;同法观察RVL对30,80mmol·L^-1的KCl引起的血管平滑肌收缩的影响;RVL对NA引起的依赖于细胞内钙和细胞外钙收缩反应的影响,以及加入N-G-硝基-L-精氨酸(L-NNA)和优降糖后RVL舒张大鼠离体主动脉环效应的变化。结果:RVL呈浓度依赖性舒张NA引起的血管收缩;无Ca²⁺ 组RVL抑制NA所致血管平滑肌收缩效应大于含Ca²⁺ 组;RVL能够拮抗NA诱发的依内钙的收缩反应,而对外钙收缩无抑制。RVL对80,30mmol·L^-1 的KCl引起的血管平滑肌收缩均有抑制作用,且前者量效曲线明显上移。L-NNA使RVL舒血管效应降低(26.0±4.6)%;优降糖组的血管舒张受抑程度与对照组无显著差别(P>0.05)。结论:RVL可呈内皮依赖性舒张血管平滑肌,其作用机制可能与该药促进NO合成释放,开放钙激活的钾通道以及抑制血管平滑肌细胞外钙内流和内钙释放有关。     

牛蒡根水提物扩血管作用及机制研究

目的: 探讨牛蒡根水提物对大鼠离体胸主动脉环的舒张作用及其作用机制。 方法: 采用测定离体血管环张力的方法,观察牛蒡根水提物（0.075~15 g·L^-1）分别对基础状态、去氧肾上腺素（PE） 5×10^-6mol·L^-1和氯化钾（KCl 40 mmol·L^-1） 预收缩的内皮完整血管环和去内皮血管环的舒张作用;并观察左旋硝基精氨酸甲酯（L-NAME, 10^-4mol·L^-1） 和亚甲蓝鸟苷酸环化酶抑制剂（ODQ, 10^-5mol·L^-1）、吲哚美辛（Indo, 10^-5mol·L^-1）、 四甲基乙二胺（TEA, 10^-4mol·L^-1）预处理对牛蒡根水提物的舒张血管作用的影响。 结果: 牛蒡根水提物对基础状态的内皮完整和去内皮血管环的张力无影响;对PE预收缩的去内皮和内皮完整血管环具有浓度依赖性舒张作用;L-NAME（P<0.01）和ODQ（P<0.05）预处理可明显减弱牛蒡根水提取物的舒血管作用,Indo预处理没有作用;TEA预处理（P<0.05）显著性增强牛蒡根水提物舒张PE预收缩血管的作用;对KCl 预收缩的内皮完整血管环有明显舒张作用。 结论: 牛蒡根水提物能引起血管发生内皮依赖性和非内皮依赖性的舒张作用,其作用机制可能涉及促进血管内皮NO释放和血管平滑肌细胞的Ca²⁺激活。     

原花青素舒张家兔主动脉和降低动脉血压的研究

目的：研究葡萄籽提取物原花青素(procyanidins，PC)舒张家兔离体主动脉和降低其动脉血压的作用及机制。方法：采用家兔离体胸主动脉环灌流模型，将标本分6组：去内皮、内皮完整、吲哚美辛(1×10^-1 mol·L^-1)、普萘洛尔(1×10^-5 mol·L^-1)、左旋硝基精氨酸N^ω-nitro-L-arginine(L-NNA 1×10^-4 mol·L^-1)或甲烯蓝(MB 1×10^-5 mol·L^-1)，分别累积加入1.25，2.5，5.0 mg·L^-1 PC观察血管张力变化；并观察40 mg·L^-1 PC对去甲肾上腺素（NA）(1×10^-8～1×10^-5 mol·L^-1)、KCl(6.3～100 mmol·L^-1)和CaCl₂ (1×10^-5～1×10^-2 mol·L^-1)诱导血管环收缩曲线的影响。另用家兔颈总动脉插管法，经静脉累积注射4.0，8.0，16，32，64，84 mg·kg^-1 PC后观察血压变化。结果：PC能舒张主动脉血管，并有量效依赖性(r=0.63，P<0.001)，去内皮、L-NNA或MB可减弱PC的舒张作用。PC能抑制NA，KCl和CaCl₂的量效收缩反应。PC能降低家兔正常动脉血压并有量效依赖性(r=0.92，P<0.001)。结论：PC舒张血管的作用是通过抑制细胞内Ca²⁺释放和电压依赖性Ca²⁺通道而减少Ca²⁺内流；也与内皮释放的NO有关；PC可降低家兔正常的动脉血压。     

苦豆子总碱舒张家兔离体主动脉的研究

目的：研究苦豆子总碱(total alkali Sophora alopecuroids L,TASa)舒张家兔离体主动脉血管的作用机制。方法：采用离体恒温灌流浴槽,以去甲肾上腺素(noradrenaline,NA)预收缩后,给予TASa(5,10,20,40 mg·L^-1)观察其舒张血管的量效关系;将标本分为对照组、TASa组、TASa+吲哚美辛(1×10^-5 mol·L^-1)、TASa+普萘洛尔(1×10^-5 mol·L^-1)、TASa+左旋硝基精氨酸(1×10^-4 mol·L^-1)和TASa+去内皮细胞6组探讨TASa舒张血管的机制;用TASa(40 mg·L^-1)温育标本后,观察TASa对NA(1×10^-8～1×10^-5 mol·L^-1),KCl(6.3～100 mmol·L^-1)和CaCl₂(1×10^-5～1×10^-2 mol·L^-1)量效收缩曲线的影响。结果：TASa能舒张主动脉血管,有量效依赖性(r=0.94,P<0.01);去内皮、左旋硝基精氨酸、吲哚美辛和普萘洛尔对TASa舒张血管的作用无明显影响;TASa能压低NA,KCl和CaCl₂的量效收缩曲线。结论：TASa可能是抑制内质网Ca²⁺释放和拮抗Ca²⁺通道,降低胞浆Ca²⁺而使血管舒张。     

黄杨宁对大鼠胸主动脉血管环舒张作用的研究

目的：研究黄杨宁（cyclovirobuxine D,CVB-D）对大鼠胸主动脉的舒张作用,并探讨其可能的作用机制。方法：分别采用氯化钾（KCl）和去氧肾上腺素（PE）预收缩血管,观察CVB-D（1×10^-5 ~6×10^-4mol·L^-1）对血管的舒张作用;将血管与6×10^-4mol·L^-1 CVB-D预孵育,观察其对KCl或PE收缩血管作用的影响;观察不同抑制剂对CVB-D舒张大鼠离体血管环作用的影响。结果：在给药浓度范围内,CVB-D对KCl或PE预收缩血管环的舒张作用呈剂量依赖性;CVB-D对内皮完整血管环的舒张作用强于对去内皮血管环的舒张作用;CVB-D与血管预孵育可抑制KCl或PE引起的血管收缩;一氧化氮合成酶（NOS）抑制剂左旋硝基精氨酸甲酯（L-NAME）或选择性一氧化氮（NO）敏感的可溶性鸟苷酸环化酶（sGC）抑制剂ODQ可阻断CVB-D的血管舒张作用。结论：CVB-D对大鼠离体胸主动脉的血管舒张作用呈剂量依赖性,其舒张作用可能与一氧化氮-可溶性鸟苷酸环化酶-环磷酸鸟苷（NO-sGC-cGMP）途径相关。     

苦碟子对大鼠胸主动脉的收缩作用及其机制

目的：研究苦碟子对大鼠离体胸主动脉环的收缩作用,并探讨其可能机制。方法：采用大鼠离体主动脉环灌流模型,观察累积质量浓度苦碟子(10～160 g·L^-1)对基础状态、苯肾上腺素(PE)和氯化钾(KCl)预收缩的内皮完整以及去内皮血管环的作用。同时以血管紧张素转换酶抑制剂卡托普利、内皮素转换酶抑制剂磷阿米酮、环氧化酶抑制剂吲哚美辛对内皮完整主动脉环预处理,然后以PE和KCl预收缩,并观察苦碟子对它们的作用,实验结果以“相对收缩力”表示。结果：苦碟子(10～160 g·L^-1)对基础状态的内皮完整和去内皮血管环的张力无影响。对PE或KCl预收缩的内皮完整血管环,苦碟子在累积质量浓度(20～160 g·L^-1)时能增强血管环的收缩作用,此作用可被卡托普利预处理所抑制,但不能被磷阿米酮及吲哚美辛预处理所抑制。苦碟子对PE或KCl预收缩的去内皮血管环无增强收缩的作用。结论：苦碟子(20～160 g·L^-1)对主动脉具有内皮依赖性收缩作用,其收缩机制可能为增强血管紧张素转换酶的活性,促进血管内皮合成血管紧张素Ⅱ,与内皮素和血栓烷A₂的作用无关。     

阿魏硝胺的血管舒张作用与机制

 目的观察阿魏酸硝酸酯类药物阿魏硝胺(FLNT)的血管舒张作用并探讨其可能机制。方法测定大鼠外周血管环(腔静脉、胸主动脉)张力,比较FLNT、硝酸甘油(NG)和硝酸异山梨酯(ISDN)对胸主动脉的舒张作用;观察鸟苷酸环化酶阻断剂亚甲蓝对FLNT血管舒张作用的影响以及FLNT对钾通道阻断剂(氯化钡、四乙胺、4-氨基吡啶和格列苯脲)血管张力的影响,研究FLNT对鸟苷酸环化酶和钾通道的作用。结果在大鼠内皮完整腔静脉,FLNT有浓度依赖性(1×10^-7～1×10^-4mol·L^-1)舒张作用。在内皮完整及去内皮胸主动脉血管上,FLNT均浓度依赖性地降低去甲肾上腺素(NE)或高钾预收缩血管的张力,对内皮没有依赖性;FLNT使NE或高钾收缩曲线非平行右移,且使最大张力减小;FLNT对胸主动脉的舒张程度类似于ISDN。FLNT可以显著地对抗无钙环境下由NE引起的血管收缩。亚甲蓝能显著减弱FLNT的胸主动脉血管舒张作用,FLNT可显著地降低氯化钡和四乙胺的血管张力。结论FLNT对大鼠胸主动脉和腔静脉产生浓度依赖性舒张,其中胸主动脉产生舒张作用类似于硝酸异山梨酯,且为非内皮依赖性的。FLNT作用机制可能其与激活鸟苷酸环化酶,开放钾通道,抑制钙通道有关。     

Mechanisms of the dilator action of the Erigerontis Herba on rat aorta

Ethnopharmacological relevance

Erigerontis Herba is widely used as a traditional Chinese medicine and is commonly used for neuroprotection and vascular protection.

Aim of study

In this study, the vasodilator effects of Erigerontis Herba (DZXX) were investigated using rat isolated aorta rings.

Material and method

The involvement of endothelium in the vasorelaxation was studied by comparing response of endothelium-intact and endothelium-denuded aorta rings which precontracted with U46619. The involvement of K⁺ channels was studied by pretreatment of the aorta rings with various K⁺ channel inhibitors. The involvement of Ca²⁺ channel was studied by incubating aorta rings with Ca²⁺-free solution, primed with U46619 prior to elicit contraction by addition of Ca²⁺ solution.

Results

DZXX (0.2–2 mg/ml) induced a concentration-dependent relaxation on U44619-precontracted aorta rings with EC₅₀ of 0.354±0.036 mg/ml. Removal of endothelium or pretreatment with a BK_Ca inhibitor iberiotoxin, K_IR inhibitor barium chloride or K_v inhibitor 4-aminopyridine produced no effect on the DZXX-induced vasorelaxation. However, pretreatment with a K_ATP inhibitor glibenclamide or a non-selective K⁺ channel inhibitor tetraethylammonium produced significant inhibition on the DZXX-induced vasorelaxation by 29.9% and 21.3%, respectively. Pretreatment with DZXX (0.4, 1.2 and 2 mg/ml) produced a concentration-dependent inhibition on Ca²⁺-induced vasoconstriction.

Conclusions

These results suggest that the vasodilator effect of DZXX was endothelium-independent, mediated by decreasing the influx of Ca²⁺ by calcium channel inhibition and increasing the influx of K⁺ by opening of a K_ATP channel.     

Vasorelaxant effects of Cerebralcare Granule are mediated by NO/cGMP pathway,potassium channel opening and calcium channel blockade in isolated rat thoracic aorta

Ethnopharmacological relevance

Cerebralcare Granule (CG), one of the famous classical recipes in traditional Chinese medicine, is developed from the “Decoction of Four Drugs”. It has been used for treatment of cerebrovascular related diseases, such as hypertension. It is well known that vasodilatation plays a very important role in hypertensive. Despite the popular medicinal use of CG, little data was available to its activity and mechanism involved in vasodilatation. Therefore, we aimed to investigate the vasorelaxant effects of CG on isolated rat thoracic aorta so as to assess some of the possible mechanisms. The present study was performed to examine the vasodilative activity of CG and its mechanisms in isolated rat thoracic aorta.

Materials and methods

CG was studied on isolated rat thoracic aorta in vitro, including endothelium-intact and endothelium-denuded aortic rings. In present study, specific inhibitors including NO synthase inhibitor N^G-nitro-l-arginine methyl ester (l-NAME), cyclooxygenase (COX) inhibitor indomethacin (INDO), non-selective K⁺ channel inhibitor tetraethylammonium chloride (TEA), K_ir channel inhibitor BaCl₂, K_ATP channel inhibitor Glibenclamide (Gli) and cholinergic receptor antagonist atropine were used, they were added 20 min before NE contraction and then added CG-induced vasodilation.

Results

Removal of endothelium or pretreatment of aortic rings (intact endothelium) with l-NAME (0.1 mM) or INDO (0.01 mM) significantly blocked the CG induced relaxation. Pretreatment with the non-selective K⁺ channel inhibitor TEA (1 mM), or the K_ir channel inhibitor BaCl₂ (0.1 mM), neither of them had no influence on the CG-induced response (p>0.05). However, pretreatment with the K_ATP channel inhibitor Gli (0.01 mM) produced significant inhibition on the CG-induced response (p<0.01). Besides, CG also inhibited the contraction triggered by NE in endothelium-denuded rings in Ca²⁺-free medium. CG (0.4, 0.8 and 3.2 mg/mL) produced rightward parallel displacement of CaCl₂ curves and reduced the maximum contraction induced by 30 mM CaCl₂ to 31.1±9.3%, 18.8±6.9% and 9.4±4.5%, respectively. The relaxation, induced by CG on endothelium-intact rat aortic rings pre-contracted with NE, was significantly attenuated in the presence of atropine (EC₅₀=3.7 mg/mL, p<0.01).

Conclusions

Our results suggest that CG induces relaxation in rat aortic rings through an endothelium-dependent pathway mediated by NO/cGMP pathway and an endothelium-independent pathway involving blockade of Ca²⁺ channels, inhibition of Ca²⁺ mobilization from intracellular stores, opening of K_ATP channel. In addition, the muscarinic receptor stimulation is also one of the vasorelaxant mechanisms.     

罗布麻叶提取物对离体大鼠胸主动脉环的舒张作用

目的:研究罗布麻叶提取物(extracts from leaves of Apocynum venetum,ELA)对离体大鼠胸主动脉环的作用及其可能的机制。方法:采用累积加药法,观察ELA对苯肾上腺素(PE)预收缩的主动脉环张力的影响;观察hemoglobin,亚甲蓝(MB)预处理对ELA扩血管作用影响;观察左旋硝基精氨酸甲酯盐酸盐(L-NAME),甲基异硫脲硫酸盐(SMT)预处理对ELA的扩血管作用的影响;观察四乙胺(TEA),4-氨基吡啶(4-AP)和格列苯脲(GLB)对ELA的血管舒张作用的影响;采用Ca2+剥夺和复加法,观察ELA对细胞内钙释放和外钙内流所引起的血管环收缩反应的作用。结果:ELA可显著舒张PE预收缩的主动脉环,低浓度下(1×10-6～3×10-4)g.mL-1为内皮依赖性作用,而高浓度下(3×10-4,1×10-3)g.mL-1则为内皮非依赖性舒张。低浓度下(1×10-6～3×10-4)g.mL-1,ELA的扩血管作用可被Hemoglobin,MB(P<0.05)和L-NAME,SMT(P<0.05)阻断。高浓度下(3×10-4～3×10-3)g.mL-1,ELA可显著抑制细胞内钙释放和细胞外钙内流(P<0.05);钾通道阻滞剂TEA,4-AP和格列苯脲可不同程度地阻断ELA扩血管作用。结论:ELA可剂量依赖性的舒张PE预收缩的胸主动脉环,呈现低浓度下内皮依赖、高浓度下内皮非依赖的特点。低浓度下ELA的血管舒张作用可能与NO释放有关,高浓度下其作用需要Ca2+,K+通道参与。     

(−)‐Epicatechin‐induced relaxation of isolated human saphenous vein: Roles of K+ and Ca2+ channels

In this study, we aimed to investigate relaxant effect of flavanol (?)‐epicatechin on the isolated human saphenous vein (HSV), as a part of its cardioprotective action, and to define the mechanisms underlying this vasorelaxation. (?)‐Epicatechin induced a concentration‐dependent relaxation of HSV pre‐contracted by phenylephrine. Among K⁺ channel blockers, 4‐aminopyridine, margatoxin, and iberiotoxin significantly inhibited relaxation of HSV, while glibenclamide considerably reduced effects of the high concentrations of (?)‐epicatechin. Additionally, (?)‐epicatechin relaxed contraction induced by 80 mM K⁺, whereas in the presence of nifedipine produced partial relaxation of HSV rings pre‐contracted by phenylephrine. In Ca²⁺‐free solution, (?)‐epicatechin relaxed contraction induced by phenylephrine, but had no effect on contraction induced by caffeine. A sarcoplasmic reticulum Ca²⁺‐ATPase inhibitor, thapsigargin, significantly reduced relaxation of HSV produced by (?)‐epicatechin. These results demonstrate that (?)‐epicatechin produces endothelium‐independent relaxation of isolated HSV rings. Vasorelaxation to (?)‐epicatechin probably involves activation of 4‐aminopyridine‐ and margatoxin‐sensitive K_V channels, BK_Ca channels, and at least partly, K_ATP channels. In addition, not only the inhibition of extracellular Ca²⁺ influx, but regulation of the intracellular Ca²⁺ release, via inositol‐trisphosphate receptors and reuptake into sarcoplasmic reticulum, via stimulation of Ca²⁺‐ATPase, as well, most likely participate in (?)‐epicatechin‐induced relaxation of HSV.     

茉莉花水提物对大鼠胸主动脉的舒张作用及机制

 目的 观察中药茉莉花水提物（AEJ）的血管舒张效应并探讨其机制。方法 采用大鼠胸主动脉环灌流,记录张力的变化;激光扫描共聚焦显微镜技术检测血管平滑肌细胞内 Ca2+浓度。结果 AEJ（0.375～6 g·L-1）能够浓度依赖性降低苯肾上腺素（PE,10 μmol·L-1)及 KCl (60 mmol·L-1)引起的主动脉环张力。在无钙环境下,AEJ 能抑制高浓度氯化钾 (KCl 60 mmol·L-1)环境下累计加入 CaCl₂(0.5～8 mmol·L-1)引起的收缩,抑制 PE (10 μmol·L-1) 引起的去内皮主动脉环的短暂收缩 (P<0.01)。钾通道阻断剂 4-氨基吡啶(5 mmol·L-1)可显著抑制 AEJ 的舒血管作用。激光扫描共聚焦检测细胞内 Ca2+的结果表明,AEJ 浓度依赖性（6,12 g·L-1）降低了 KCl 除极诱导的滑肌细胞胞浆内 Ca2+的升高幅度（P<0.05）。结论 AEJ 能够浓度依赖性舒张大鼠胸主动脉,其作用机制可能是减少 Ca2+经电压依赖性钙通道和受体操纵性钙通道流入血管平滑肌细胞及抑制内质网内 Ca2+释放有关;电压敏感型 K+通道（K_V）的激活部分参与了 AEJ 舒血管作用。     

复方当归汤含药肠吸收液舒张血管平滑肌的研究

目的:研究复方当归汤含药肠吸收液舒张血管平滑肌的作用.方法:取大鼠小肠制成翻转囊,置于复方当归汤粗提液中温孵2h,取肠囊内K-R液即得复方当归汤含药肠吸收液.采用大鼠离体胸主动脉环灌流模型,观察累积浓度含药肠吸收液对基础状态、苯肾上腺素(PE)预收缩、氧化钾预收缩血管环的作用,并与硝苯地平比较.结果:复方当归汤含药肠吸收液对基础状态或氯化钾预收缩的血管环无明显影响;当含药肠吸收液中指标成分阿魏酸浓度累积达2.48 × 10-3,4.96×10-3,9.92×10-3g·L-1时,可剂量依赖性抑制PE预收缩的血管环收缩(P＜0.05).硝苯地平对基础状态预收缩的血管环无明显影响;当浓度累积达8.66×10-4,17.32 × 10-4,34.65 × 10 -4mmol·L-1时,可剂量依赖性抑制PE或氯化钾预收缩的血管(P＜0.05,或P＜0.01).结论:复方当归汤含药肠吸收液对完整内皮的PE预处理的血管有舒张作用,含药肠吸收液可用于中药复方离体药效学研究.     

Hypotensive effect of Aspidosperma subincanum Mart. in rats and its mechanism of vasorelaxation in isolated arteries

Ethnopharmacological relevance

Aspidosperma subincanum is a medicinal herb that is known to be useful for the treatment of cardiovascular-related illnesses. However, its effects and pharmacological mechanisms of action have not been studied. The aim of the present study was to determine the effect of an ethanol extract of Aspidosperma subincanum (EEAS) on blood pressure (in vivo) and vascular tension (in vitro) in the rat thoracic aorta.

Materials and methods

Catheters were inserted into the right femoral vein and artery of anesthetized rats for EEAS infusion and the measurement of blood pressure, heart rate and aortic blood flow (flow probes were placed around the aorta). Moreover, the vasodilator effect of EEAS in isolated pre-contracted rat aortas was examined.

Results

Intravenous infusion of EEAS resulted in significant and dose-dependent hypotension, bradycardia and increased aortic blood flow. In isolated arteries, EEAS (0–27 μg/mL) induced a concentration-dependent relaxation of pre-contracted aortic rings; endothelial denudation potentiated this effect. Pre-treatment of the aortic rings with ODQ, an inhibitor of soluble guanylyl cyclase (sGC); MDL-12,330A, an inhibitor of adenylyl cyclase (AC); or CPA, a SERCA inhibitor, reduced EEAS-induced vasorelaxation. Treatment with an EEAS impaired contractions induced by phenylephrine (an adrenergic agonist) and Bay K 8644 (an L-type Ca²⁺ channel activator). The blockade of K⁺ channels with tetraethylammonium, clotrimazole, glibenclamide or 4-aminopyridine reduced the relaxation stimulated by EEAS.

Conclusions

These findings suggest that EEAS induces hypotension associated with bradycardia. EEAS induces endothelium-independent vascular relaxation. The sGC/cGMP and AC/cAMP pathways, SERCA activation and Ca²⁺ and K⁺ flux across the sarcolemma, are likely involved in this relaxation.