Ca++ channel blocking activity of Artemisia scoparia extract

Intravenous administration of a hydro-methanolic extract of Artemisia scoparia (3–30 mg/kg) produced hypotensive and bradycardiac effects. These effects remained unaltered in atropine treated animals and the presence of the extract did not modify the vasoconstrictor response of norepinephrine, indicating that cardiovascular effects of the plant extract are not mediated through activation of muscarinic receptors or adrenoceptor blockade. In the in vitro studies, it suppressed the spontaneous movements of rabbit jejunum in a concentration-dependent (0.1-1 mg/mL) manner. The plant extract inhibited K⁺-induced tonic contraction in a manner similar to that of verapamil. Exposure of tissue to Ca⁺⁺-free Kreb's solution abolished the spontaneous movements which were restored on addition of Ca⁺⁺. In tissue pretreated with plant extract or verapamil, addition of Ca⁺⁺ (50 μM) failed to restore spontaneous contractions. These data indicate that Artemisia scoparia cntains Ca⁺⁺ channel blocker-like constituent(s) which may explain the hypotensive effect observed in vivo and the traditional use of the plant as a spasmolytic.     

Hypotensive and spasmolytic activities of ethanolic extract of Capparis cartilaginea

An ethanolic extract of Capparis cartilaginea (CC) at a dose of 1–10 mg/kg caused a dose-dependent fall in blood pressure and heart rate in anaesthetized rats. These effects were not blocked by atropine (1 mg/kg) and pretreatment with CC did not alter the pressor response to norepinephrine, indicating that the cardiovascular effects of CC are independent of cholinergic or adrenergic receptor involvement. In spontaneously beating guinea-pig atria, CC induced a concentration-dependent (0.1–1 mg/mL) decrease in force and rate of atrial contractions. In rabbit thoracic aorta, CC caused inhibition of norepinephrine or K⁺-induced contractions. In guinea-pig ileum, CC (1 mg/mL) inhibited submaximal contractions induced by acetylcholine, histamine or 5-HT. Spontaneous contractions of rat uterus were also abolished when CC was added to the tissue bath at similar concentrations. These results suggest that the direct relaxant action of CC on myocardium and blood vessels may be responsible for its hypotensive and bradycardiac effects observed in the in vivo studies. Moreover, CC exhibits general spasmolytic activity in different smooth muscle preparations.     

Blood pressure lowering,cardiovascular inhibitory and bronchodilatory actions of Achillea millefolium

Achillea millefolium Linn. (Asteraceae) is used in folk medicine for the treatment of overactive cardiovascular and respiratory ailments. This study describes its hypotensive, cardio‐depressant, vasodilatory and bronchodilatory activities. The crude extract of Achillea millefolium (Am.Cr) caused a dose‐dependent (1–100 mg/kg) fall in arterial blood pressure of rats under anaesthesia. In spontaneously beating guinea‐pig atrial tissues, Am.Cr exhibited negative inotropic and chronotropic effects. In isolated rabbit aortic rings, Am.Cr at 0.3–10 mg/mL relaxed phenylephrine (PE, 1 µm ) and high K⁺ (80 mm )‐induced contractions, as well as suppressed the PE (1 µm ) control peaks obtained in Ca⁺⁺‐free medium, like that caused by verapamil. The vasodilator effect of Am.Cr was partially blocked by N_ω‐nitro‐l ‐arginine methyl ester in endothelium intact preparations. In guinea‐pig tracheal strips, Am.Cr inhibited carbachol (CCh, 1 µm ) and K⁺‐induced contractions. These results indicate that Achillea millefolium exhibits hypotensive, cardiovascular inhibitory and bronchodilatory effects, thus explaining its medicinal use in hyperactive cardiovascular and airway disorders, such as hypertension and asthma. Copyright © 2010 John Wiley & Sons, Ltd.     

Pharmacological screening of (+)-Multifloramine from Colchicum decaisnei

(+)-Multifloramine (1) isolated from Colchicum decaisnei (Liliaceae) exhibited significant positive inotropic and negative chronotropic effects on isolated rat atria. The positive inotropic effect was not antagonized by adding propranolol. The compound showed hypotensive and tocolytic activities. The LD₅₀ of the compound in mice was found to be 383 mg/kg body weight. Its quaternary methiodide derivative (2) produced less effect on atria, uterus and mean arterial blood pressure. The LD₅₀ of the derivative in mice was 31.6 mg/kg body weight.     

C-fiber-evoked autonomic cardiovascular effects after injection of Piper betle inflorescence extracts

Piper betle inflorescence extracts contain eugenol (6.2%) and safrole (78.9%). Intravenous injections of water extracts of P. betle inflorescence (PBE), eugenol, and safrole in rats induced hypotensive and bradycardiac effects, whereas both intraarterial and intrathecal injections of PBE, eugenol and safrole resulted in hypotensive and tachycardiac effects. Moreover, the effects of intravenous injections of PBE were reversed or inhibited by the pretreatment with bilateral vagotomy, atropine (1 mg/kg, i.p.) and capsaicin (100 mg/kg, s.c.). Effects of intraarterial injections of PBE on blood pressure were inhibited by the pretreatment with substance P (SP) antagonist (1 nmol, i.t.) and clonidine (2.5 μg, i.t.), while heart rate was only inhibited by the pretreatment with SP antagonist (1 nmol, i.t.). In addition, the tachycardia resulting from intrathecal injections of PBE was inhibited by pretreatment with propranolol (0.3 mg/kg, i.v.). Eugenol and safrole induced the same pattern on blood pressure and heart rate changes as PBE in rats after various treatments. This report suggests that acute administration of betel inflorescence extracts by different routes may activate C-fiber-evoked parasympathetic and sympathetic cardiovascular reflexes in rats.     

The Prokinetic,Laxative, and Antidiarrheal Effects of Morus nigra: Possible Muscarinic,Ca2+ Channel Blocking,and Antimuscarinic Mechanisms

Morus nigra Linn. (black mulberry) is used in gastrointestinal ailments. This study demonstrates gut modulatory properties of M. nigra. The prokinetic, laxative, and antidiarrheal activities of M. nigra were assessed in mice, while isolated rabbit jejunum and guinea‐pig ileum were used to explore insight into mechanism(s). At 30 and 70 mg/kg, the crude extract of M. nigra (Mn.Cr) exhibited atropine‐sensitive prokinetic and laxative effects, similar to carbachol (CCh). While at higher doses (100, 300, and 500 mg/kg), Mn.Cr offered protection against castor oil‐induced diarrhea. In rabbit jejunum, Mn.Cr and its chloroform fraction inhibited CCh‐induced contractions more potently compared with high K⁺ (80 mm ). Conversely, petroleum fraction was more potent against high‐K⁺‐induced contractions. At 0.01 mg/mL, Mn.Cr caused a parallel shift in acetylcholine concentration–response curves (CRCs) followed by a non‐parallel shift at 0.03 mg/mL, similar to dicyclomine. At further tested concentrations, Mn.Cr (0.1 and 0.3 mg/mL) and petroleum fraction suppressed Ca²⁺ CRCs, similar to verapamil. In guinea‐pig ileum, Mn.Cr, its aqueous and ethyl acetate fractions exhibited atropine‐sensitive gut stimulant activity along with additional uncharacterized excitatory response in the aqueous fraction only. These results suggest that black mulberry possesses prokinetic, laxative, and antidiarrheal effects, putatively mediated through cholinomimetic, antimuscarinic, and Ca²⁺ antagonist mechanisms, respectively. Copyright © 2016 John Wiley & Sons, Ltd.     

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.     

Antidiarrhoeal activity of Hypoxis hemerocallidea Fisch. & C. A. Mey. (Hypoxidaceae) Corm (‘African potato’) aqueous extract in rodents

This study investigated the antidiarrhoeal activity of Hypoxis hemerocallidea corm aqueous extract (APE) on experimentally‐induced diarrhoea, gastrointestinal motility, intestinal transit and enteropooling in rodents. H. hemerocallidea corm aqueous extract (APE, 50–400 mg/kg, p.o.) produced dose‐dependent and significant (p < 0.05–0.01) protection of rats and mice against castor oil‐induced diarrhoea, inhibited intestinal transit and delayed gastric emptying. Like atropine (1 mg/kg, p.o.), APE (50–400 mg/kg, p.o.) produced dose‐dependent and significant (p < 0.05–0.01) antimotility effect, and caused dose‐related inhibition of castor oil‐induced enteropooling in the animals. Like loperamide (10 mg/kg, p.o.), APE (50–400 mg/kg, p.o.) dose‐dependently and significantly (p < 0.05–0.01) delayed the onset of castor oil‐induced diarrhoea, decreased the frequency of defaecation and reduced the severity of diarrhoea in the rodents. Compared with control animals, APE (50–400 mg/kg, p.o.) dose‐dependently and significantly (p < 0.05–0.01) decreased the volume of castor oil‐induced intestinal fluid secretion, and reduced the number, weight and wetness of faecal droppings. APE (50–400 mg/mL) also produced concentration‐related and significant (p < 0.05–0.01) inhibitions of the spontaneous, pendular contractions of the rabbit isolated duodenum, and attenuated acetylcholine (ACh, 0.1–5.0 µg/mL)‐induced contractions of the guinea‐pig isolated ileum. Although the precise mechanism of the antidiarrhoeal activity of APE could not be established, the results of this study indicate that APE possesses antidiarrhoeal activity. This finding supports the use of ‘African potato’ as a natural supplementary remedy for the treatment, management and/or control of diarrhoea in some rural communities of southern Africa. Copyright © 2009 John Wiley & Sons, Ltd.     

Studies on antihypertensive and antispasmodic activities of methanol extract of Acacia nilotica pods

A methanol extract of Acacia nilotica pods (AN) caused a dose-dependent (3-30 mg/kg) fall in arterial blood pressure. Treatment of animals with atropine abolished the vasodilator response of acetylcholine (ACh), whereas the antihypertensive effect of the plant extract remained unaltered. Phentolamine (an alpha-adrenergic blocker) abolished the vasoconstrictor effect of norepinephrine (NE), whereas pretreatment of the animal with AN, did not modify the NE response. These results indicate that the antihypertensive effect of plant extract is independent of muscarinic receptor stimulation or adrenoceptor blockade. In the in vitro studies, AN produced a dose-dependent (0.3-3.0 mg/mL) inhibitory effect on force and rate of spontaneous contractions in guinea-pig paired atria. Similarly, it inhibited the spontaneous contraction of rabbit jejunum in a concentration-dependent (0.1-3.0 mg/mL) manner. AN also inhibited K(+)-induced contractions in rabbit jejunum at a similar concentration range, which suggests that the antispasmodic action of AN is mediated through calcium channel blockade, and this may also be responsible for the blood pressure lowering effect of AN, observed in the in vivo studies.     

Antispasmodic and blood pressure lowering effects of Valeriana wallichii are mediated through K+ channel activation

Crude extract of Valeriana wallichii rhizome (Vw.Cr) and its fractions were studied for possible antispasmodic and blood pressure lowering activities to rationalize some of the folkloric uses. In rabbit jejunum preparations, Vw.Cr (0.1–3.0 mg/mL) caused relaxation of spontaneous contractions. When tested against high K⁺ (80 mM)-induced contractions it produced weak inhibitory effect, while caused complete relaxation of the contractions induced by low K⁺ (20 mM). In the presence of glibenclamide (3 μM), the inhibitory effect of low K⁺ was shifted to the right, similar to that produced by cromakalim while, verapamil caused no differentiation in its inhibitory effect against low and high K⁺-induced contractions. In guinea pig ileum, the plant extract produced similar results as in rabbit jejunum. Intravenous administration of Vw.Cr, produced fall in arterial blood pressure in normotensive anaesthetized rats and this effect was partially blocked by glibenclamide. In rabbit aortic preparations, plant extract also caused a selective and glibenclamide-sensitive relaxation of low K⁺ (20 mM)-induced contractions. Activity-directed fractionation studies revealed that the observed activity was distributed both in the chloroform and aqueous fractions. These results indicate that the antispasmodic and hypotensive effects of Valeriana wallichii are mediated possibly through K_ATP channel activation, which justify its use in gastrointestinal and cardiovascular disorders.     

Antiinflammatory Effects of an Ethyl Acetate Extract of Euphorbia royleana

The antiinflammatory activity of the ethyl acetate extract (EA) from the residue of an 85% alcohol extract of the latex of plant Euphorbia royleana was tested in mice and rats. In acute tests EA displayed marked antiinflammatory activity. Significant antiarthritic activity was observed in subacute and chronic models of formaldehyde-induced arthritis, adjuvant-induced developing and established arthritis. It produced inhibition of the exudate volume and the leucocyte migration in rats and vascular permeability in mice. EA showed a poor inhibitory effect on the granuloma formation by cotton pellet and croton oil. In in vitro studies EA inhibited the spontaneous contractions of the isolated pregnant rat uterus and oxytocin-induced contractions of virgin rat uterus. It had a very low ulcerogenic potential. The oral LD₅₀ in both rats and mice was more than 2500 mg/kg.     

Antispasmodic,bronchodilator and blood pressure lowering properties of Hypericum oblongifolium – possible mechanism of action

The crude extract of Hypericum oblongifolium (Ho.Cr), which tested positive for flavonoids, saponins and tannins caused concentration‐dependent (0.1–1.0 mg/mL) relaxation of spontaneous and high K⁺ (80 mM)‐induced contractions in isolated rabbit jejunum preparations, suggesting a Ca⁺⁺ antagonistic effect, which was confirmed when pretreatment of the tissue with Ho.Cr produced a rightward shift in the Ca⁺⁺ concentration‐response curves, like that caused by verapamil. Ho.Cr relaxed carbachol (1 μM) and high K⁺‐induced contractions in guinea pig tracheal preparations. It caused a dose‐dependent (3–100 mg/kg) fall in arterial blood pressure of rats under anesthesia. In isolated guinea pig atria, Ho.Cr caused inhibition of both atrial force and rate of spontaneous contractions. When tested in rabbit aortic rings, Ho.Cr exhibited a vasodilator effect against phenylephrine (1 μM) and high K⁺‐induced contractions. These results indicate that Ho.Cr possesses gastrointestinal, respiratory and cardiovascular inhibitory effects, mediated via a Ca⁺⁺ antagonist mechanism. Copyright © 2009 John Wiley & Sons, Ltd.     

Action of compounds from Mandevilla velutina on croton oil-induced ear oedema in mice. A comparative study with steroidal and nonsteroidal antiinflammatory drugs

The antioedematogenic activity of two natural pregnane compounds from Mandevilla velutina was evaluated against croton oil-induced ear oedema in mice. For comparison the effects of nonsteroidal (indomethacin, phenidone and BW 755C) and steroidal (dexamethasone) antiinflammatory drugs were analysed. The purified compounds from M. velutina MV8612 (3 and 30 mg/kg, i.p.) and to a lesser extent MV8608 (30 and 100 mg/kg; i.p.), given 30 min prior to the croton oil, significantly inhibited this oedema, maximal inhibition (MI) of 53% and 26%, respectively. However, given orally 180 min after, neither compound had any effect. Compound MV8612 but not MV8606 (200–600 μg/ear) given 180 min after the irritant significantly inhibited croton oil-induced oedema, MI of 29%. Indomethacin given topically (0.05–0.2 mg/ear) 180 min after, but not orally (1–10 mg/kg), significantly inhibited this oedema, MI of 30%, while phenidone administered either orally (100 and 300 mg/kg) or topically (2 mg/ear) 180 min after caused partial inhibition, MI of 24% and 18%, respectively. BW 755C, given topically (0.1 and 0.5 mg/ear) but not orally (10–300 mg/kg) 180 min after, was also effective in inhibiting croton oil oedema, MI of 18%. Dexamethasone given either topically (0.05–0.2 mg/ear) or orally (0.25-1 mg/kg) 30 and 60 min prior potently inhibited croton oil oedema, MI of 86% and 79%, respectively. These results indicate that the natural compounds MV8612 and to a lesser extent MV8608 isolated from M. velutina, besides their antibradykinin activity, exhibited both topical and systemic long-lasting antioedematogenic effects against croton oil-induced ear oedema in mice.     

Cardiovascular active substances from the straw mushroom,Volvariella volvacea

The straw mushroom Volvariella volvacea is one of the common edible mushrooms in Hong Kong and is widely cultivated in Southeast Asian countries. It has been reported to produce a hypotensive response in animals including humans. An aqueous extract of the mushroom (SME) was prepared and given through intravenous injections to normotensive rats. The blood pressure changes produced by SME alone or in the presence of various drugs were studied. The effects of SME on the kidney function of water-loaded rats and on isolated tissue preparations of the tail artery and right atrium were examined. An i.v. injection of SME produced a hypotensive effect in rats with an ED₅₀ of 25 mg dry weight/kg body weight. This hypotensive effect of SME was attenuated or blunted in the presence of hexamethonium, phentolamine, pyrilamine and cimetidine suggesting the involvement of the α-adrenergic component of the autonomic system and/or histamineergic stimulation. SME did not increase urinary excretion nor sodium diuresis. It produced positive chronotropic and inotropic effects on isolated right atria and induced contraction of isolated tail artery strips. This latter contractile response was inhibited by antagonists of serotonin and α-adrenoceptor, ketanserin and phentolamine respectively. Partial purification using dialysis and liquid chromatography revealed that the hypotensive active substances had molecular masses between 8000 and 12000 dalton. These substances were heat stable and resistant to trypsin digestion. In view of the similarity in blood pressure and cardiovascular response, SME might contain serotonin-like substances.     

Pharmacological effects of the aqueous extract of Neorautanenia mitis in rodents

The pharmacological effects of the aqueous extract of Neorautanenia mitis (family Papilonaceae) were studied in rodents. Investigations were carried out on acetic acid-induced writhing (pain) in mice and hind paw oedema in rats. The effects of the extract were also studied on the isolated non-pregnant rat uterus and rabbit jejunum. Results showed the extract to possess significant (P<0.05) dose-dependent anti-nociceptive activity between 12.5 and 50.0 mg/kg p.o. in mice and slight anti-inflammatory activity at 25 and 50 mg/kg p.o. in rats. The extract also produced a concentration-dependent inhibition of the normal rhythmic contraction of the isolated non-pregnant rat uterus. It was found to inhibit oxytocin-induced as well as acetylcholine-induced contractions in the rat uterus. The extract also exhibited concentration-dependent inhibition of spontaneous contractions of the rabbit jejunum. Preliminary phytochemical analysis of the extract revealed the presence of saponin glycosides, flavonoids, tannins and alkaloids. The extract had an intraperitoneal (i.p.) LD(50) of 282.84+/-3.2 mg/kg in mice. These data corroborate the traditional use of this plant in the treatment of dysmenorrhea.     

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.     

Muscarinic agonist properties of the hydrobutanol extract from aerial parts of Waltheria viscosissima St. Hil. (Sterculiaceae) in Rats†

The cardiovascular effects of the hydrobutanol phase of the ethanolíc extract from the aerial parts (HBWV) of Waltheria viscosissima A. St. Hil. (Sterculiaceae) were tested in rats by using a combined (in vivo and in vitro) approach. HBWV (5, 7.5, 10, 15 and 20 mg/kg, randomly) induced a significant and dose‐dependent hypotension and bradycardia in conscious freely moving normotensive rats. Both hypotensive and bradycardic effects evoked by a submaximal dose of HBWV (10 mg/kg) were inhibited by pre‐treatment of the animals with atropine (2 mg/kg, i.v.). In anaesthetized animals, electrocardiogram recordings revealed second and third degree sinoatrial and atrioventricular blockade induced by the extract (10 mg/kg, i.v.), which were inhibited by cardiac muscarinic blockade (atropine, 2 mg/kg, i.v.). In isolated rat aortic rings, increasing concentrations of HBWV (50, 100, 200 and 400 µg/mL) were able to antagonize the contractile effects of noradrenaline (1 µM ). This effect was inhibited by pre‐incubation of the aortic rings with atropine (1 µM ), by removal of the vascular endothelial tissue or by nitric oxide synthase blockade. These results suggest that both cardiac and peripheral actions induced by HBWV are probably mediated by stimulation of cardiac and endothelial muscarinic receptors, respectively. Copyright © 1999 John Wiley & Sons, Ltd.     

Hypoglycaemic properties of the aqueous root extract of Morinda lucida (Benth) (Rubiaceae). Studies in the mouse

The aqueous root extract of Morinda lucida (Rubiaceae) Benth, exhibited potent hypoglycaemic effects in both normoglycemic and alloxan-induced diabetic mice by oral administration. This effect was dose-dependent and more potent than that observed with chlorpropamide (1-(p-chlorobenzene-sulphanyl)-3-propylurea). In the normoglycaemic mice, the extract (140 mg/kg body weight) produced a fall in blood sugar of 32% + 1% while at 280 mg/kg body weight there was a 52% + 2% fall over the same time interval. In alloxan-induced diabetic mice, the reaction time of the extract was longer with a single dose of the extract producing a significant hypoglycaemic effect 4 h after administration. In diabetic mice, a dose of 140 mg/kg body weight of the plant extract caused a fall in blood sugar of 51% + 1% while a dose of 280 mg/kg produced a fall of 60% + 2%.     

Pharmacological Basis for Medicinal Use of Lens culinaris in Gastrointestinal and Respiratory Disorders

Crude extract of Lens culinaris (Lc.Cr), which tested positive for presence of anthraquinones, flavonoids, saponins, sterol, tannins, and terpenes exhibited protective effect against castor oil‐induced diarrhea in mice at 100–1000 mg/kg. In rabbit jejunum preparations, Lc.Cr caused relaxation of spontaneous contractions at 0.03–5.0 mg/mL. Lc.Cr inhibited carbachol (CCh, 1 μM) and K⁺ (80 mM)‐induced contractions in a pattern similar to dicyclomine, but different from verapamil and atropine. Lc.Cr shifted the Ca⁺⁺ concentration‐response curves to the right, like dicyclomine and verapamil. Pretreatment of tissues with Lc.Cr (0.03–0.1 mg/mL) caused leftward shift of isoprenaline‐induced inhibitory CRCs, similar to papaverine. In guinea‐pig ileum, Lc.Cr produced rightward parallel shift of CCh curves, followed by non‐parallel shift at higher concentration with suppression of maximum response, similar to dicyclomine, but different from verapamil and atropine. Lc.Cr (3.0–30 mg/kg) caused suppression of carbachol (CCh, 100 µg/kg)‐induced increase in inspiratory pressure of anesthetized rats. In guinea‐pig trachea, Lc.Cr relaxed CCh and high K⁺‐induced contractions, shifted CCh curves to right and potentiated isoprenaline response. These results suggest that L. culinaris possesses antidiarrheal, antispasmodic, and bronchodilator activities mediated possibly through a combination of Ca⁺⁺ antagonist, anticholinergic, and phosphodiesterase inhibitory effects, and this study provides sound mechanistic background to its medicinal use in disorders of gut and airways hyperactivity, like diarrhea and asthma. Copyright © 2014 John Wiley & Sons, Ltd.     

Linalool‐rich Rosewood Oil Induces Vago‐vagal Bradycardic and Depressor Reflex in Rats

Cardiovascular effects of the linalool‐rich essential oil of Aniba rosaeodora (here named as EOAR) in normotensive rats were investigated. In anesthetized rats, intravenous (i.v.) injection of EOAR induced dose‐dependent biphasic hypotension and bradycardia. Emphasis was given to the first phase (phase 1) of the cardiovascular effects, which is rapid (onset time of 1–3 s) and not observed in animals submitted to bilateral vagotomy or selective blockade of neural conduction of vagal C‐fibre afferents by perineural treatment with capsaicin. Phase 1 was also absent when EOAR was directly injected into the left ventricle injection, but it was unaltered by i.v. pretreatment with capsazepine, ondansetron or HC030031. In conscious rats, EOAR induced rapid and monophasic hypotensive and bradycardiac (phase 1) effects that were abolished by i.v. methylatropine. In endothelium‐intact aortic rings, EOAR fully relaxed phenylephrine‐induced contractions in a concentration‐dependent manner. The present findings reveal that phase 1 of the bradycardiac and depressor responses induced by EOAR has a vago‐vagal reflex origin resulting from the vagal pulmonary afferents stimulation. Such phenomenon appears not to involve the recruitment of C‐fibre afferents expressing 5HT₃ receptors or the two chemosensory ion channels TRPV₁ and TRPA₁. Phase 2 hypotensive response appears resulting from a direct vasodilatory action. Copyright © 2013 John Wiley & Sons, Ltd.