Analgesic and anti-inflammatory activities of the crude hydroalcoholic extract obtained from the bark of Hymenaea martiana

Experiments were designed to examine the analgesic and anti-inflammatory activities of the crude hydroalcoholic extract (CE) of Hymenaea martiana. The CE of H. martiana (25-200 mg/kg, i.p.) caused a graded inhibition of hindpaw oedema induced by carrageenan, PAF-acether (PAF), serotonin (5-HT), dextran and histamine (HIS). However, the CE given orally up to 500 mg/kg had no effect on the agonist-induced hindpaw oedema. The CE given intraperitoneally, but not orally, caused a graded and pronounced inhibition of His, 5-HT, bradykinin (BK) and PAF-induced increase of vascular permeability. When the CE was given orally (300 mg/kg) once a day for 15 days it caused a significant increase of agonist-induced increase of vascular permeability. The CE given either by p.o. or by i.p. routes (100-800 mg/kg) dose-dependently inhibited arachidonic acid (AA)-induced ear oedema in mice, being significantly more potent when it was given by the latter route. In contrast, CE at the same doses, failed to inhibit croton-oil-induced ear oedema in mice. The CE of H. martiana given by either i.p. or p.o. routes caused a marked and dose-dependent antinociceptive activity as revealed by its antagonistic action against acetylcholine, acetic acid or AA-induced writhing responses in mice, being more effective when given intraperitoneally. These results, and those previously reported with the CE of H. martiana in the isolated preparations, provide strong experimental support which argues in favour of the beneficial use of this plant extract in folk medicine. The exact mechanism that underlies its analgesic and anti-inflammatory profiles remains unclear, but may result from its ability to inhibit the generation of lipoxygenase and/or cyclooxygenase products of the arachidonic acid pathway.     

Differential antagonistic effect of hydroalcoholic extract from Hymenaea martiana hayne arzeik on kinin and other agonist-induced contractions of the isolated rat uterus and Guinea-pig ileum

This study was undertaken to evaluate the action of the hydroalcoholic extract (HE) from the bark of Hymenaea martiana on bradykinin (BK), lysyl-bradykinin (L-BK), acetylcholine (ACh), angiotensin II (AII), prostaglandin F_2a (PGF_2a), serotonin (5-HT), oxytocin (Ot) and histamine (His)-induced contractions of the isolated rat uterine muscle and guinea-pig ileum. The HE (50–200 μg/mL) added to the bath for 20 min caused a concentration-dependent rightward displacement of BK, L-BK and ACh-induced contractions in the rat uterus, allied to a discrete but significant reduction of maximal responses to the latter two agonists. By contrast, at the same range of concentrations the HE antagonized in a concentration-dependent but noncompetitive manner the contractions induced by AII, but only at high concentrations (200 μg/mL) it significantly inhibited contractions evoked by both PGF_2a and Ot, while contractile responses induced by 5-HT were not affected. In the guinea-pig ileum, the HE of H. martiana (50 and 100 μg/ml) caused a discrete rightward displacement of the BK and ACh concentration—response curves. Higher concentrations of the HE of H. martiana (200 μg/mL) caused a marked depression of BK and ACh-induced maximal responses. These findings show that the active principle(s) presents in the HE from the bark of H. martiana exhibits an interesting pharmacological profile against several neurotransmitter-induced contractions in nonvascular smooth muscles. Such actions may be relevant for supporting, at least in part, the use of this plant in folk medicine.     

Evaluation of pharmacological activity of a crude hydroalcoholic extract from Jatropha elliptica

The pharmacological effect of the hydroalcoholic extract of Jatropha elliptica was analysed in in vivo and in vitro models. When given orally in mice, the extract showed a low acute toxicity (LD₅₀ 5 g/kg). In a dose of 0.5 or 1 g/kg p.o. the extract did not interfere with diuresis in the rat, but was found to be effective in blocking rat paw oedema induced by carrageenan and partially, serotonin-induced oedema. In the same dose, the extract failed to inhibit rat paw oedema induced by dextran and the increase of rat cutaneous vascular permeability caused by Bothrops Jararaca venom, dextran, histamine, PAF-acether and serotonin. Pre-incubation of the isolated rat uterus and guinea-pig ileum with the extract (0.2–0.8 mg/mL), produced a concentration-related and non-competitive inhibition of contractions induced by acetylcholine and bradykinin. However, the extract was about 2-fold more potent in inhibiting the contraction of both agonists in guinea-pig ileum than in rat uterine muscle. In rat aorta, the extract (50–100 μg/mL) caused a concentration-dependent inhibition of noradrenaline-evoked contractions, being about 5-fold more potent when compared to the IC₅₀ values obtained in rat uterus.     

8-甲氧基补骨脂素对家兔离体肺动脉和主动脉的作用

 目的：研究中药白花前胡有效成分8-甲氧基补骨脂素(8-MOP)时肺动脉(PA)是否有选择性抑制作用。方法：观察了8-MOP对去甲肾上腺素(NE)诱发家兔离体PA及MOP对去甲肾上腺素(NE)诱发家兔离体PA及主动脉(AR)标本收缩作用剂量反应曲线和两种收缩组分的影响。结果：8-MOP使PA及AR标本对NE的收缩剂量反应曲线右移,最大反应降低,并表现出对PA的作用明显强于对AR的作用;8-MOP对NE所致的离体PA及AR引起的依内源性钙收缩有显著抑制作用,对NE所致PA依外源性钙收缩亦有一定的抑制作用,而对AR的NE所致依外源性钙收缩则无抑制作用。结论：8-MOP对PA主要通过抑制细胞内Ca²⁺的释放及外Ca²⁺内流而发挥较高选择性 抑制作用。     

Endothelium-dependent vasodilator effect of extract prepared from the seeds of Areca catechu on isolated rat aorta

Arecae semen extract relaxed aortic ring preparations of isolated rat aorta that contained endothelium from 3×10⁻⁷ g/mL, reaching a maximum of 86% at 10⁻⁵ g/mL. Its relaxation did not occur in specimens without endothelium, and was inhibited by pretreatment with 10⁻⁴ M N^G-nitro-1-arginine methylester. One of the active components was arecoline which is a muscarinic receptor agonist. Another active component was condensed tannin contained in Arecae semen. © 1997 John Wiley & Sons, Ltd.     

Effects of an aqueous extract of Terminalia arjuna on isolated rat atria and thoracic aorta

Terminalia arjuna (Combretaceae) is used traditionally in ayurveda, to treat a variety of cardiovascular disorders. The aims of this study were to characterize the positive inotropic effect of the aqueous extract of T. arjuna bark in isolated paced rat left atria and to study its effects on a vascular smooth muscle preparation, the rat thoracic aorta. The crude and semipurified aqueous extracts produced a positive inotropic effect of rat atria and the maximum contraction was comparable to that produced by isoprenaline. The positive inotropic effect of the extract was completely blocked by a β-adrenoceptor blocker, propranolol, and an uptake-1 blocker, cocaine. In precontracted aorta, the aqueous extract produced a contraction followed by relaxation. Propranolol did not block the relaxant effect of the aqueous extract. It is concluded that the positive inotropic effect of the aqueous extract was mediated via an action on β₁-adrenoceptors and was likely to be due to the release of noradrenaline from the sympathetic nerve endings. The vasorelaxant effect of the extract, however, was not mediated via an action on β₂ adrenoceptor.     

Vasorelaxant effect of stilbenes from rhizome extract of rhubarb (Rheum undulatum) on the contractility of rat aorta

The vascular relaxant effect of the rhizome extract of Rheum undulatum was evaluated with isolated rat thoracic aorta preparations. The methanol extract of the rhizome induced a concentration-dependent relaxation of aortic preparations precontracted with 0.3 microm phenylephrine (EC50 value: 5.8 microg/mL). The activity-guided fractionation of the extract led to the isolation of seven hydroxystilbene components as active principles, i.e. piceatannol, resveratrol, desoxyrhapontigenin, rhapontigenin, piceid, rhaponticin and epsilon-viniferin. Of these, piceatannol, a tetrahydroxystilbene, exhibited the most potent vascular relaxant effect in rat aortic preparations (EC50 value 2.4 microm). The vasorelaxant effect of piceatannol on endothelium-intact aorta rings was diminished completely by the removal of functional endothelium or by pretreatment of the aortic tissues with N(G)-nitro-l-arginine methyl ester. These results suggest that piceatannol may be the major mediator responsible for the vasorelaxing properties of the rhizome extract of Rheum undulatum and the vasorelaxant effects of the piceatannol may be mediated via endothelium-dependent nitric oxide signaling pathway.     

Effects of aqueous extract of Baphia nitida on isolated cardiac tissues

The pharmacological action of cold aqueous extract of fresh leaves of Baphia nitida was studied on cardiac preparations. The extract (5.0 × 10^?3 g mL) reduced the rate and force of contraction of the isolated rabbit heart. The rate and force of contraction of the spontaneously beating rat atria was dose-dependently reduced by 5.0 × 10^?4 to 2.5 × 10^?2 g/mL of the extract and this effect was not antagonized by 3.45 × 10^?7 M atropine. The extract (5.0 × 10^?2 g mL) completely blocked the positive chronotropic and inotropic effects of 10 mM CaCI² but only reduced that of 1.61 × 10^?7 M isoprenaline. The effect of the extract on CaCI₂-induced responses of the rat atria was not affected by 3 × 10^?7 M propranolol. The use of this extract for treating palpitation locally may be related to its negative chronotropic and inotropic effects.     

Smooth muscle relaxant activities of compounds isolated from malaysian medicinal plants on rat aorta and guinea-pig ileum

Muscle relaxant activities of six compounds isolated from Malaysian medicinal plants were investigated on the smooth muscles of the rat aorta and longitudinal muscle of the guinea-pig ileum. Except for goniothalamin, the other five compounds exhibited varying degrees of muscle relaxant activities on the two smooth muscles. Dicentrine, isocorydine, altholactone and usnic acid reduced the contractions to KCI and phenylephrine in the rat aorta, whilst atranorin slightly reduced the contractions to phenylephrine but not KCI. In addition, dicentrine and isocorydine markedly reduced the contractile response to phenylephrine in Ca²⁺-free Krebs solution. In the longitudinal muscle of the guinea-pig ileum, altholactone, atranorin, dicentrine and isocorydine inhibited to a greater extent the phasic than the tonic responses to KCI. All four compounds similarly inhibited the contractions induced by ACh. The results suggest that the relaxant activities of the compounds are attributed mainly to inhibition of Ca²⁺ influx via the calcium channels in the membrane of the smooth muscles. Furthermore, the greater sensitivity of dicentrine, isocorydine and altholactone against phenylephrine-induced contractions or KCI-induced phasic contractions are due to their abilities to inhibit intracellular Ca²⁺ release in these muscles.     

Relaxant effects of the neutral extract of the leaves of Bidens pilosa Linn on isolated rat vascular smooth muscle

The long-lasting antihypertensive effect of a neutral extract of Bidens pilosa has been suggested to be due to vasodilation. The present work was undertaken to assess this hypothesis. The vasorelaxant effect of a neutral extract (NBp) of the leaves of B. pilosa was evaluated in vitro on isolated rat aorta contracted with KCl or norepinephrine. NBp induced a concentration-dependent vasorelaxation of the rat aorta precontracted with KCl (60 mM) by 25%-105% at the respective concentrations of 0.25-1.5 mg/mL. The maximal concentration of 1.5 mg/mL provoked 88% relaxation of norepinephrine-induced contractions. There were no significant differences between the effects of the extract on the aorta strips with or without endothelium. In the presence of indomethacin or pyrilamine maleate, the relaxant response induced by the plant extract was significantly inhibited at the lower concentrations. The plant extract was able to reduce the aorta resting tone, inhibit the KCl-induced contractions (90% at 1.5 mg/mL) and the CaCl2-induced contractions by 95% at a concentration of 0.75 mg/mL. These results demonstrate the vasodilating properties of the neutral extract of Bidens pilosa and indicate that it may act as a calcium antagonist.     

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。     

Arbutus unedo induces endothelium-dependent relaxation of the isolated rat aorta

Arbutus unedo L. (Ericaceae) is used in oriental Morocco to treat arterial hypertension. We studied its vasodilator effect and mechanisms of action in vitro. The root aqueous extract of Arbutus (0.25 mg/mL) produced a relaxation of noradrenaline-precontracted ring preparations of rat aorta with intact endothelium. Relaxation by Arbutus did not occur in specimens without endothelium and was inhibited by pretreatment with 100 microM N(G)-methyl-L-arginine (L-NMA), 10 microM methylene blue or 50 microM 1H-[1,2,4] oxadiazolo [4,3-a] quinoxaline-1-one (ODQ) but not by 10 microM atropine. These results suggest that Arbutus produces an endothelium-dependent relaxation of the isolated rat aorta which may be mediated mainly by a stimulation of the endothelial nitric oxide synthase by mechanisms other than activation of muscarinic receptors.     

Chemical and pharmacological analysis of the crude aqueous/alcoholic extract from Cordyline dracaenoides

Chemical analysis of Cordyline dracaenoides (Kunth) demonstrated the presence of steroidal saponins and anthocyanidins in the stem, rhizome and root. Small amounts of tannins were also detected in its stem and rhizome. Pharmacological analysis revealed different effects according to the part of the plant used. Crude aqueous/alcoholic extract (CE) from the rhizome inhibited carrageenan-induced rat paw oedema, while the CE obtained from the root significantly decreased the locomotor activity and potentiated barbiturate-induced hypnosis in mice. The CE from the roots inhibited noradrenaline-induced contraction in the rat vas deferens in a concentration-dependent and a noncompetitive manner, while the CE from the rhizome caused a parallel displacement to the left of noradrenaline concentration response curves. In the isolated rat stomach, the CE from the roots promoted a concentration-dependent displacement to the right of the serotonin concentration response curve allied to a marked inhibition of its maximal response, while the CE from the rhizome produced only an inhibition of about 40% of serotonin-contractile responses. These results suggest that the CE from C. dracaenoides exhibits a potent and long lasting antioedematogenic effect, has central depressant effects and potentiates noradrenaline-induced contractile responses of the isolated rat vas deferens. All these effects may be, at least in part, related to the presence of steroidal saponins in this plant.     

Terminalia arjuna extract modulates the contraction of rat aorta induced by KCl and norepinephrine

The bark of Terminalia arjuna is in clinical use for the management of cardiovascular disorders in India. The objective of this study was to investigate the contractile response induced by the extract on rat aorta, a vascular smooth muscle. Terminalia arjuna relaxed the contraction, induced by both KCl (60 mM ) and norepinephrine (NE, 3 μM ). Inhibition was more prominent (80%) in the NE induced contraction than the KCl induced contraction (30%). Under similar conditions diltiazem, a calcium channel blocker (Dz, 1.0 μM ), inhibited 68% of the KCl induced and 30% of NE induced contraction. Thus it appears that the action of Terminalia arjuna extract differs from that of diltiazem in that it is more specific for alpha-adrenergic receptor agonists. It indirectly inhibited the contraction induced by norepinephrine by acting on K (Ca) channel by hyperpolarizing the smooth muscle membrane.     

Tannins and catechin gallate mediate the vasorelaxant effect of Arbutus unedo on the rat isolated aorta

This study examined the vascular effect of Arbutus leaves (aqueous extract) and described the isolation of several fractions responsible for their vasorelaxant activity. The aqueous extract (AE) of leaves was tested on rat aortic rings precontracted with 0.1 microm noradrenaline. At 10(-2) g/L, AE produced an endothelium dependent relaxation of 66% +/- 5%, (n = 8). The leaves of Arbutus were then extracted successively with different solvents and the methanol extract was the most active. When tannins (primarily condensed tannins) were precipitated from the methanol extract, they showed a strong vasorelaxant activity (87% +/- 4%, n = 5), whereas the elimination of tannins in the methanol extract reduced significantly its vasorelaxant activity (42% +/- 8%, n = 8, p < 0.005). The methanol extract was further separated semi-preparatively by reversed-phase HPLC. Four fractions (Fr2, Fr3, Fr4 and Fr6) were the most active and produced 88% +/- 2% (n = 5), 75% +/- 6% (n = 5), 76% +/- 3% (n = 7) and 77% +/- 3% (n = 10) relaxation, respectively. These four fractions mainly correspond to polyphenol compounds. Analysis of Fr6 indicated that this fraction contained catechin gallate. In conclusion, the vasorelaxant activity of Arbutus is likely to be due to polyphenol compounds, primarily condensed tannins and catechin gallate.     

藏药1号水提液对大鼠离体胸主动脉条收缩作用的影响

目的：通过观察藏药1号水提液对大鼠离体胸动脉条收缩作用的影响研究其降压机制。方法：观察藏药1号水提液(6mg／mL)和维拉帕米(Ver0.013mg／mL)对高K^ 液引起的主动脉条收缩的时效影响，对KCl，NE及CaCl2引起的大鼠主动脉条收缩的量效曲线的影响，以及对NE引起的依赖于细胞内钙及细胞外钙的收缩的影响。结果：藏药1号水提液抑制高K^ 液引起的主动脉收缩；且可使KCl、NE及CaCl2引起的大鼠主动脉条收缩的量效曲线非平行右移，最大效应降低，呈非竞争性拮抗作用：与维拉帕米相似，对NE引起的依赖于细胞内钙及细胞外钙的收缩均有抑制作用。结论：提示藏药1号的降压机制与钙离子通道拮抗剂一致。     

Herbal medicine Catuama induces endothelium-dependent and -independent vasorelaxant action on isolated vessels from rats,guinea-pigs and rabbits

The present study was designed to examine the vasorelaxant action of the herbal medicine Catuama and the hydroalcoholic extracts (HE) of each plant present in this product and to compare their effects with that caused by acetylcholine (ACh) in intact (⁺E) or in endothelium-rubbed (⁻E) rings of rat thoracic aorta (RA), guinea-pig pulmonary artery (GPPA), guinea-pig mesenteric artery (GPMA), rabbit pulmonary artery (RPA), rabbit mesenteric artery (RMA) precontracted with noradrenaline (NA) or phenylephrine (PE). The extract of Catuama (1-3000 μg/mL) produced graded relaxation of RA, ⁺E or ⁻E, with mean EC₅₀ of 430 μg/mL and ≊ 3000 μg/mL and E_max of 81 % ± 15 % and 47% ± 4 %, respectively. The nitric oxide (NO) synthase inhibitor, N^ω-nitro-L -arginine (L -NOARG, 100 μM ), inhibited in vasorelaxant action (p < 0.05) in RA (⁺E), while indomethacin (3 μM ), propranolol (1 μM ), glibenclamide (1 μM ), methylene blue (10 μM ) and apamin (0.1 μM ) had no significant effect. ACh (1-1000 μM ) caused graded relaxation in RA with ⁺E, these effects being markedly antagonized by L -NOARG (100 μM ), methylene blue (10 μM ) and partially by apamin (0.1 μM ), but not by indomethacin (3 μM ), glibenclamide (1 μM ) or propranolol (1 μM ). The Catuama extract (1-3000 μg/mL) produces partial relaxations in rings of RMA (mean EC₅₀ of 1073 μg7/ml and E_max of 56 % ± 13 %), an effect which was antagonized by L -NOARG (100 μM ). In RPA (⁺E) the extract produces partial relaxation followed by contraction (E_max 28 % ± 6 %), an effect which was abolished by L -NOARG (100 μM ) or methylene blue (10 μM ). The extract caused graded relaxation in rings of GPPA and GPMA with mean EC₅₀ values of 60 μg/mL and 1148 μg/mL and E_max 96% ± 2% and 88% ± 12%, respectively. L -NOARG (100 μM ) blocked the Catuama extract vasorelaxation in GPPA and only partially in GPMA, but markedly antagonized the vasorelaxations caused by ACh in both GPPA andRMA. The HE Paullinea cupana, Zinziber officinalis and Trichilia catigua (1-3000 μg/mL) caused a graded vasorelaxant effect ⁺E of RA with a mean EC₅₀ of 22, 55 and 1793 μg/mL and E_max 100%, 86% ± 7% 70% ± 2%, respectively. In addition the HE of P. cupana also caused graded relaxation in ⁻E of RA with EC₅₀ and E_max of 233 μg/mL and 100%, respectively, while T. catigua and Z. officinalis produced partial relaxation in RA ⁺E. In contrast the HE of Ptychopetalum olacoides caused little contraction (46% ± 14%). These results demonstrate that the medicinal herb Catuama produces significant vasorelaxation responses in vessels from different animal species, and show that its effects are in great part dependent on the release of NO or NO-derived substances. Our results also demonstrate that the vasorelaxant action of the product Catuama seems to be due to the action of the active principles present mainly in P. cupana; T. catigua and, to a lesser extent, in Z. officinalis. Such results may contribute to the explanation of its beneficial effect of Catuama herbal medicine in the management of cardiovascular disturbances. © 1997 John Wiley & Sons, Ltd.     

Cardiovascular effects of Urtica dioica L. in isolated rat heart and aorta

Urtica dioica L. or Nettle (Urticaceae) is widely used in oriental Morocco to treat hypertension. Aqueous extract of Nettle (AEN) also exerts a hypotensive action in the rat in vivo. The aim of this work was to characterize the specific cardiac and vascular effects of AEN. In the isolated Langendorff perfused rat heart, AEN (1 and 2 g/l) markedly decreased heart rate and increased left ventricular pressure. Higher concentration (5 g/l) even led to cardiac arrest. Although carbachol mimicked the bradycardiac effect of AEN, atropine (a muscarinic receptor antagonist, 1 micro M) did not modify the response. Beside its action on myocardium, AEN also affected vascular contractility. Indeed, AEN (0.1-5 g/l) produced a dose-dependent increase in basal tone of isolated rat aorta. This effect was endothelium independent and was abolished by 1 micro M prazosin (an alpha1-adrenergic antagonist). AEN had little additional effects when the aorta was precontracted by noradrenaline (1 micro M) or KCl (40 mM). Our data indicate that AEN produces a vasoconstriction of the aorta which is due to activation of alpha1-adrenergic receptors. However, AEN also induces a strong bradycardia through non-cholinergic and non-adrenergic pathways which might compensate for its vascular effect and account for the hypotensive action of Urtica dioica L described in vivo.     

拳参正丁醇提取液对家兔胸主动脉条收缩的影响

目的:研究拳参正丁醇提取液(PBNA)对家兔离体胸主动脉条的作用。方法:采用家兔离体胸主动脉条,高钾去极化后,以不同浓度CaCl2为刺激剂,观察PBNA对其量-效曲线的影响;以NE为血管收缩刺激剂,观察PBNA对内钙释放与外钙内流的影响。结果:(1)低剂量PBNA(0.1mg/ml)可抑制高钾去极化引起的动脉条收缩,使CaCl2量-效曲线右移,最大反应性降低,高剂量PBNA(0.4mg/ml)可增强高钾去极化引起的动脉条收缩;(2)低剂量的PBNA抑制NE诱导的内钙释放所致的血管收缩反应,而高剂量的PBNA增强NE诱导的内钙释放所致的血管收缩反应;各剂量的PBNA对复钙后NE所致的血管收缩作用具有抑制趋势。结论:不同浓度的PBNA通过抑制或促进平滑肌细胞膜电压依赖Ca2 通道而对家兔主动脉条的收缩起双重效应,PBNA对受体操纵的Ca2 通道也具有一定的抑制作用,对K 通道的开放有一定的促进作用。     

Relaxant effect of ethanol extract of Bacopa monniera on trachea,pulmonary artery and aorta from rabbit and guinea-pig

The relaxant action of an ethanol extract of Bacopa monniera was examined on ring segments of pulmonary arteries (guinea-pig and rabbit), aorta (rabbit) and tracheal preparations (guinea-pig). The plant extract induced relaxation in all the tissues in a dose-dependent manner. Guinea-pig main pulmonary artery was found to be the most responsive to the plant extract, however, complete relaxation was obtained in the tracheal preparations. The relaxant response to the plant extract was unaffected by pretreatment of the blood vessels with either atropine or propranolol, whereas in the tracheal preparations propranolol partially blocked the response. Indomethacin reduced the plant extract-induced relaxation in all the tissues. In blood vessels relaxation induced by the plant extract was not modified in the presence or absence of the endothelial layer. These results suggest that relaxation induced by Bacopa monniera possibly involves prostacyclin compounds (in all the tissues) and β-adrenoceptors (in tracheal preparations). Furthermore, this relaxation is independent of endothelium and muscarinic receptors activation. © 1997 John Wiley & Sons, Ltd.