(−)‐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.     

The Different Effects of Resveratrol and Naringenin on Isolated Human Umbilical Vein: The Role of ATP‐Sensitive K+ Channels

The blood flow from the placenta to the fetus depends on human umbilical vein (HUV) vascular tone. ATP‐sensitive K⁺ (K_ATP) channels link the metabolic state of the cell to membrane potential, and their activation in the HUV represents protection against hypoxia. The aims of our study were to assess the effects of resveratrol and naringenin on the HUV and to define the roles of K_ATP channels in their effects. Serotonin or 100 mM K⁺ were used for precontraction of the HUV without endothelium. The cumulative concentration–response curves were obtained by adding increasing concentrations of resveratrol or naringenin. Glibenclamide was used, in order to test the role of K_ATP channels in its effect. Resveratrol induced more potent vasodilatation of serotonin‐ and 100 mM K⁺‐precontracted HUV than naringenin. Glibenclamide induced significant shift to the right of the concentration–response curves of resveratrol and P1075 (a specific opener of K_ATP channels). Western blotting showed that HUV expressed protein Kir6.1. Thus, resveratrol and naringenin produce dilatation of HUV. It seems that K_ATP channels are involved in the relaxation of HUV induced by resveratrol, while naringenin seems to interact with other ion channels. The K⁺ channel‐independent mechanism(s) of these polyphenols could not be excluded. Copyright © 2014 John Wiley & Sons, Ltd.     

Bisnordihydrotoxiferine and vellosimine from Strychnos divaricans root: Spasmolytic properties of bisnordihydrotoxiferine

Bisnordihydrotoxiferine and vellosimine, two tertiary indole alkaloids have been isolated from the root of Strychnos divaricans. Bisnordihydrotoxiferine antagonized in a nonspecific manner, oxytocin and acetylcholine induced contractions in the rat uterus and acetylcholine and histamine responses in the guinea-pig ileum. Bisnordihydrotoxiferine, like verapamil, produced effects on voltage dependent Ca²⁺ channels. For example in guinea-pig ileum, bisnordihydrotoxiferine (pD'₂ 3.92±0.09) and verapamil (pD'₂ 6.00±0.11) inhibited KCl induced contractions. Furthermore, bisnordihydrotoxiferine (pD'₂ 4.37±0.02) and verapamil (pD'₂ 6.83±0.10) also antagonized CaCl₂ induced contractions of K⁺-depolarized rat uterus. When compared with sodium nitroprusside, an antagonist of receptor operated Ca²⁺ channels, bisnordihydrotoxiferine had no effect. However, in the aorta, the alkaloid (IC₅₀, 6.10 × 10^?6M) antagonized the intracellular calcium dependent transient contractions of noradrenaline and it was about four times more potent than procaine (IC₅₀, 2.30 × 10^?5M), a known inhibitor of the release of Ca²⁺ from intracellular stores. Bisnordihydrotoxiferine may produce nonspecific spasmolytic actions mainly by inhibiting intracellular calcium mobilization and to a lesser extent by inhibiting voltage dependent calcium channels in smooth muscles.     

Mechanisms of the relaxant effect of a Danshen and Gegen formulation on rat isolated cerebral basilar artery

Aim of the study

Danshen (root of Salvia miltiorrhiza) and Gegen (root of Pueraria lobata) are two herbs used in traditional Chinese medicine, most commonly for their putative cardioprotective and anti-atherosclerotic effects. In this study, the actions of a Danshen and Gegen formulation (DG; ratio 7:3) were investigated on rat-isolated cerebral basilar artery.

Materials and methods

Rat basilar artery rings were precontracted with 100 nM U46619. Involvement of endothelium-dependent mechanisms was investigated by mechanical removal of the endothelium; K⁺ channels were investigated by pretreatment of the artery rings with various K⁺ channel inhibitors, and Ca²⁺ channels were investigated in artery rings incubated with Ca²⁺-free buffer and primed with 100 nM U46619 for 5 min prior to adding CaCl₂ to elicit contraction.

Results

DG produced concentration-dependent relaxation of the artery rings with an IC₅₀ of 895 ± 121 μg/ml. Mechanical removal of the endothelium or pretreatment with the BK_Ca channel inhibitor iberiotoxin (100 nM), the K_V channel inhibitor 4-aminopyridine (1 mM), or the K_IR channel inhibitor barium chloride (100 μM), all had no effect on the DG-induced response (P > 0.05 for all). However, pretreatment with the K_ATP channel inhibitor glibenclamide (1 μM), the non-selective K⁺ channel inhibitor tetraethylammonium (TEA, 100 mM), or a combination of all the K⁺ channel inhibitors (iberiotoxin + 4-aminopyrindine + barium chloride + glibenclamide + TEA) produced significant inhibition on the DG-induced response (P < 0.01 for all); its maximum vasorelaxant effect (Imax) was reduced by 37, 24, and 30%, respectively. Preincubation of the artery rings with DG for 10 min produced concentration-dependent (1, 3 and 7 mg/ml) and total inhibition on the CaCl₂-induced vasoconstriction.

Conclusions

These findings suggest the vasorelaxant effect of DG on rat basilar artery is independent of endothelium-derived mediators, whereas, inhibition of Ca²⁺ influx in the vascular smooth muscle cells is important, and a minor component is mediated by the opening of K_ATP channels. DG could be a useful cerebroprotective agent in some patients with occlusive cerebrovascular disease.     

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.     

Relaxant effect of flavonoid naringenin on contractile activity of rat colonic smooth muscle

Ethnopharmacological relevance

Disturbed gastrointestinal (GI) motility can be associated with smooth muscle abnormalities and dysfunction. Exploring innovative approaches that can modulate the disturbed colonic motility are of great importance for clinical therapeutics. Naringenin, a flavonoid presented in many traditional Chinese herbal medicines, has been shown to have a relaxant effect on different smooth muscles. The aim of the present study was to investigate the effect of naringenin on regulation of GI motility.

Material and methods

Mechanical recording was used to investigate the effect of naringenin on isolated rat colonic smooth muscle spontaneous contractions. Whole cell patch clamp, intracellular [Ca²⁺] concentration ([Ca²⁺]_i) and membrane potential measurements were examined on primary cultures of colonic smooth muscle cells (SMCs). A neostigmine-stimulated rat model was utilized to investigate the effect of naringenin in vivo.

Results

Naringenin induced a concentration-dependent inhibition (1–1000 μM) on rat colonic spontaneous contraction, which was reversible after wash out. The external Ca²⁺ influx induced contraction and [Ca²⁺]_i increase were inhibited by naringenin (100 μM). In rat colonic SMCs, naringenin-induced membrane potential hyperpolarization was sensitive to TEA and selective large-conductance calcium-activated K⁺ (BK_Ca) channel inhibitor iberiotoxin. Under whole cell patch-clamp condition, naringenin stimulated an iberiotoxin-sensitive BK_Ca current, which was insensitive to changes in the [Ca²⁺]_i concentration. Furthermore, naringenin significantly suppressed neostigmine-enhanced rat colon transit in vivo.

Conclusion

Our results for the first time demonstrated the relaxant effect of flavonoid naringenin on colon smooth muscle both in vitro and in vivo. The relaxant effect of naringenin was attributed to direct activation of BK_Ca channels, which subsequently hyperpolarized the colonic SMCs and decreased Ca²⁺ influx through VDCC. Naringenin might be of therapeutic value in the treatment of GI motility disorders.     

The source of ca2+ for the spasmolytic actions of longicaudatine,a bisindole alkaloid isolated from Strychnos trinervis (Vell.) Mart. (Loganiaceae)

Longicaudatine, a tertiary bisindole alkaloid isolated from the root bark of Strychnos trinervis (Vell.) Mart. (Loganiaceae), antagonized in a noncompetitive manner, carbachol and histamine induced contractions of the guinea-pig ileum and bradykinin responses in the rat uterus. The respective pD₂' values (mean ± SE) were 4.61 ± 0.21, 4.98 ± 0.04 and 4.49 ± 0.01. Longicaudatine, unlike verapamil, had no effect on voltage dependent Ca²⁺ channels, as it failed to inhibit KCI or CaCl₂ induced contractions of guinea-pig ileum and depolarized rat uterus respectively. When compared with sodium nitroprusside, an antagonist of receptor operated Ca²⁺ channels, longicaudatine produced a slower and weaker inhibition of noradrenaline induced sustained contractions of rabbit aortic strips. However, in the aorta, the alkaloid antagonized the intracellular calcium dependent transient contractions of noradrenaline and longicaudatine (IC₅₀, 5.01 × 10^?7 M) was approximately 133 times more potent that procaine (IC₅₀, 6.68 × 10^?5 M), a known inhibitor of the release of Ca²⁺ from intracellular stores. Longicaudatine may exert nonspecific spasmolytic effects by acting on intracellular Ca²⁺ stores, rather than on depolarization dependent or receptor operated Ca²⁺ channels.     

Mechanisms of Vasorelaxation Induced by Hexahydrocurcuminin Isolated Rat Thoracic Aorta

This study was designed to examine the vasorelaxant effects of hexahydrocurcumin (HHC), one of the major natural metabolites of curcumin from Curcuma longa, on rat isolated aortic rings, and the underlying mechanisms. Isometric tension of the aortic rings was recorded using organ bath system. HHC (1 nM to 1 mM) relaxed the endothelium‐intact aortic rings pre‐contracted with PE and KCl in a concentration‐dependent manner. Removal of the endothelium did not alter the effect of HHC‐induced relaxation. In Ca²⁺‐free Krebs solution, HHC significantly inhibited the CaCl₂‐induced contraction in high K⁺ depolarized rings and suppressed the transient contraction induced by PE and caffeine in a concentration‐dependent manner. HHC was also observed to relax phobal‐12‐myristate‐13‐acetate (PMA), an activator of protein kinase C (PKC), precontracted aortic rings in a concentration‐dependent manner with EC₅₀ values equivalent to 93.36 ± 1.03 μM. In addition, pre‐incubation with propranolol (a β‐adrenergic receptor blocker) significantly attenuated the HHC‐induced vasorelaxation. These results suggest that the vasorelaxant effect of HHC is mediated by the endothelium‐independent pathway, probably because of the inhibition of extracellular Ca²⁺ influx through voltage‐operated Ca²⁺ channels and receptor‐operated Ca²⁺ channels, the inhibition of Ca²⁺mobilization from intracellular stores, as well as inhibition of PKC‐mediated Ca²⁺‐independent contraction. Moreover, HHC produces vasorelaxant effects probably by stimulating the β‐adrenergic receptor. Copyright © 2015 John Wiley & Sons, Ltd.     

Inhibitory effects of Cistus populifolius on contractile responses in the isolated rat duodenum

The medicinal plant Cistus populifolius L., shows an important dose-dependent spasmolytic activity. The ability of the Cistus extract to inhibit both acetylcholine (ACh) (3.4 × 10⁻⁸–6.8 × 10⁻⁵ M) and CaCl₂ (2 × 10⁻⁴–1.28 × 10⁻² M) -induced contractions and the relaxing effect on K⁺ (75 mM) -induced contractions may indicate a non-specific receptor antagonist. However, this action may be related to the influx of extracellular Ca²⁺. These antispasmodic effects are partly consistent with the use of C. populifolius in folk medicine for certain gastrointestinal disorders.     

Tracheal relaxation of five Ivorian anti-asthmatic plants: role of epithelium and K⁺ channels in the effect of the aqueous-alcoholic extract of Dichrostachys cinerea root bark

Ethnopharmacological relevance

Leaves of Boerhavia diffusa (Nyctaginaceae), Baphia nitida, Cassia occidentalis, Desmodium adscendens (Fabaceae), and root bark of Dichrostachys cinerea (Fabaceae) are used in Ivory Coast for the treatment of asthma. The aim of this study was to evaluate the potential airway relaxant activity of different extracts of these plants.

Materials and methods

Extracts of different polarities (H₂O, EtOH/H₂O, MeOH and CH₂Cl₂) were obtained from these five plants. Their ex vivo relaxant activity was tested in mice isolated trachea precontracted with carbachol (1 μM).

Results

Cumulative concentrations of most extracts induced moderate to strong relaxation, the methanolic extracts being the most potent and the polar extracts the most active at the concentrations used, supporting the traditional use of these five plants as anti-asthmatic remedies. We further investigated the molecular and cellular mechanisms of the mouse trachea relaxant effect of the aqueous-alcoholic extract of Dichrostachys cinerea root bark, the most potent extract. Its effect was not modified in the presence of β-adrenoceptor antagonists (propranolol or ICI 118,551) or a PKA inhibitor (H89). By contrast, it was decreased after depolarization-induced precontraction (with 80 mM KCl), in the presence of some K⁺ channels blockers [4-aminopyridine as voltage-dependent K⁺ (K_v) channel blocker and tetraethylammonium chloride as large conductance Ca²⁺-activated K⁺ (BK_Ca) channel blocker, but not with glibenclamide, an ATP-sensitive K⁺ (K_ATP) channel blocker] or after epithelium removal.

Conclusions

The mouse tracheal relaxant effect of Dichrostachys cinerea EtOH/H₂O extract was independent of β₂-adrenoceptors activation and cAMP/PKA pathway, but dependent on epithelium and K⁺ channels, namely K_v and BK_Ca channels. Further investigation will be required to identify the component(s) responsible for this airways relaxant activity.     

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。     

天钩降压胶囊对家兔主动脉血管条收缩反应的影响

目的:观察天钩降压胶囊对家兔主动脉条收缩反应的影响,探讨其降压作用机制.方法:将家兔离体主动脉条置于灌流肌槽中,记录天钩降压胶囊提取物对去甲肾上腺素(NE)、氯化钾(KCl)、氯化钙(CaCl2)诱导的主动脉条收缩作用的影响,以及对NE诱导的主动脉条细胞内钙及细胞外钙依赖性收缩反应的影响.结果:天钩降压胶囊1,3,5g·L-1剂量组均能使NE,CaCl2引起的主动脉条最大收缩反应降低(P＜0.01);对NE诱发主动脉条细胞内钙及细胞外钙依赖性收缩均有明显抑制(P＜0.01),对细胞外钙依赖性收缩的抑制作用更显著;对KCl引起的动脉条收缩反应无明显影响.结论:天钩降压胶囊可通过影响细胞内钙离子浓度促进血管平滑肌舒张从而发挥降压作用.其机制可能主要通过影响受体操纵的Ca2+通道(ROC),对电压依赖性Ca2+通道(PDC)作用不显著.对NE诱发主动脉条细胞外钙依赖性收缩的抑制作用优于对细胞内钙依赖性收缩的作用.     

人参皂苷Rb1配伍乌头碱对新生大鼠心肌细胞ATP酶及相关离子的影响

目的:探讨人参皂苷Rb_1配伍乌头碱对心肌细胞三磷酸腺苷(ATP)酶及相关离子的影响。方法:采用胰蛋白酶消化和差速贴壁法培养大鼠乳鼠心肌细胞,分为正常组、乌头碱组、人参皂苷Rb_1组、乌头碱配伍人参皂苷Rb_1(1∶1,1∶2,2∶1)组,给药作用1 h,检测各组心肌细胞的细胞活力和心肌细胞体内离子浓度和ATP酶活力。结果:0.2%乌头碱能降低心肌细胞活力,降低心肌细胞内Mg2+和K+浓度,升高Ca2+和Na+的浓度,降低Ca2+-ATP酶,Na+-K+-ATP酶和Ca2+-Mg2+-ATP酶活力;人参皂苷Rb_1配伍乌头碱后能提高心肌细胞内Mg2+和K+浓度,降低心肌细胞内Ca2+和Na+浓度,提高Ca2+-ATP酶,Na+-K+-ATP酶和Ca2+-Mg2+-ATP酶活力。结论:人参皂苷Rb_1可减弱乌头碱致心肌细胞毒性,机制可能与调节心肌细胞膜ATP酶活性及细胞内相关离子的浓度有关。     

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.     

Species Differences in the Antidiarrheal and Antispasmodic Activities of Lepidium sativum and Insight into Underlying Mechanisms

The aim of this study was to see if the crude extract of Lepidium sativum (Ls.Cr) exhibits species specificity in its antidiarrheal and antispasmodic activities along with insight into the underlying mechanisms using the in‐vivo and in‐vitro experiments. Ls.Cr inhibited castor oil‐induced diarrhea in mice at doses (300 and 1000 mg/kg) three times higher dose than for rats. In isolated rat ileum and jejunum, Ls.Cr completely inhibited carbachol (CCh), low K⁺ (25 mM) and high K⁺ (80 mM)‐induced contractions, while in guinea‐pig tissues, Ls.Cr caused complete inhibition of only CCh‐induced contraction. In rabbit tissues, Ls.Cr completely inhibited CCh and low K⁺‐induced contractions sensitive to K⁺ channel antagonists. Pretreatment of guinea‐pig and rat tissues with Ls.Cr caused a rightward shift in CCh‐induced contractions in a pattern similar to dicyclomine, while in rabbit and rat tissues, Ls.Cr shifted isoprenaline curves to the left similar to papaverine. These data indicate that the antidiarrheal and antispasmodic activities of L. sativum are species dependent, mediating its antispasmodic effect through combinations of multiple pathways including activation of K⁺ channels, and inhibition of muscarinic receptors, Ca⁺⁺ channels and PDE enzyme. Rat tissues showed the highest potency. Based on the results, we recommend using multiple species to know the real pharmacological profile of medicinal products. Copyright © 2012 John Wiley & Sons, Ltd.     

Pharmacological basis for the medicinal use of Zanthoxylum armatum in gut,airways and cardiovascular disorders

This study describes the gut, airways and cardiovascular modulatory activities of Zanthoxylum armatum DC. (Rutaceae) to rationalize some of its medicinal uses. The crude extract of Zanthoxylum armatum (Za.Cr) caused concentration‐dependent relaxation of spontaneous and high K⁺ (80 mM)‐induced contractions in isolated rabbit jejunum, being more effective against K⁺ and suggestive of Ca⁺⁺ antagonist effect, which was confirmed when pretreatment of the tissues with Za.Cr shifted Ca⁺⁺ concentration‐response curves to the right, like that caused by verapamil. Za.Cr inhibited the castor‐oil‐induced diarrhea in mice at 300–1000 mg/kg. In rabbit tracheal preparations, Za.Cr relaxed the carbachol (1 μM) and high K⁺‐induced contractions, in a pattern similar to that of verapamil. In isolated rabbit aortic rings, Za.Cr exhibited vasodilator effect against phenylephrine (1 μM) and K⁺‐induced contractions. When tested in guinea pig atria, Za.Cr caused inhibition of both atrial force and rate of spontaneous contractions, like that caused by verapamil. These results indicate that Zanthoxylum armatum exhibits spasmolytic effects, mediated possibly through Ca⁺⁺ antagonist mechanism, which provides pharmacological base for its medicinal use in the gastrointestinal, respiratory and cardiovascular disorders. Copyright © 2009 John Wiley & Sons, Ltd.     

Pharmacological Studies on the Antispasmodic,Bronchodilator and Anti‐Platelet Activities of Abies webbiana

This study evaluated the antispasmodic, bronchodilator and anti‐platelet activities of Abies webbiana to rationalize some of its folk uses in gut and airways disorders and inflammation. The crude extract of A. webbiana (Aw.Cr) caused a complete relaxation of both spontaneous and K⁺ (80 mM)‐induced contractions in isolated rabbit jejunum in a concentration‐dependent manner. Aw.Cr shifted the Ca⁺⁺ concentration–response curves (CRCs) to the right, in a fashion similar to verapamil, confirming its Ca⁺⁺ channel blocking (CCB) effect. In isolated rabbit tracheal preparations, it caused relaxation of carbachol (1 μM) and K⁺ (80 mM)‐induced contractions comparable to verapamil suggesting that the bronchodilatory effect may possibly be mediated through CCB activity. Aw.Cr was found to be the inhibitor of both ADP‐ and epinephrine‐induced aggregation of human platelets thereby suggesting therapeutic potential in this plant against thrombo‐embolic conditions. The exhibited anti‐platelet effect was observed at low doses against epinephrine as compared to ADP. This study confirmed the presence of spasmolytic activity in Abies webbiana through possible blockade of Ca⁺⁺ channels providing evidence for its folkloric use in gut and respiratory disorders in addition to anti‐platelet activity. Copyright © 2014 John Wiley & Sons, Ltd.     

Mechanisms of the cerebral vasodilator actions of isoflavonoids of Gegen on rat isolated basilar artery

Ethnopharmacological relevance

Gegen (root of Pueraria lobata) is used in traditional Chinese medicine for treatment of cardiovascular diseases. In this study, the relaxant actions of three of its isoflavonoids; puerarin, daidzein, and daidzin, were investigated on rat-isolated cerebral basilar artery.

Materials and methods

Rat basilar artery rings were precontracted with 100 nM U46619. Involvement of endothelium-dependent mechanisms was investigated by mechanical removal of the endothelium and inhibitors of nitric oxide synthase (NOS) and cyclooxygenase (COX) enzymes. Adenylyl cyclase- and guanylyl cyclase-dependent pathways were investigated using their respective inhibitors 9-(tetrahydro-2-furanyl)-9H-purine-6-amine (SQ22536) and 1H-[1,2,4]oxadiazolo [4,3-[alpha]]-quinoxalin-1-one (ODQ). K⁺ channels were investigated by pretreatment of the artery rings with various K⁺ channel inhibitors, and Ca²⁺ channels were investigated in artery rings incubated with Ca²⁺-free buffer and primed with 100 nM U46619 for 5 min prior to adding CaCl₂ to elicit contraction.

Results

Puerarin, daidzein, and daidzin produced concentration-dependent relaxation of the artery rings with concentration that produced 50% inhibition (IC₅₀) of 304 ± 49 μM, 20 ± 7 μM, and 140 ± 21 μM, respectively. Removal of the endothelium produced no change on their vasorelaxant responses except the maximum response (I_max) to puerarin was inhibited by 28%. The NOS inhibitor N^G-nitro-l-arginine methyl ester (L-NAME; 100 μM) also produced 45% inhibition on the puerarin-induced vasorelaxant response, but not the COX inhibitor flurbiprofen (10 μM). SQ22536 (100 μM) and ODQ (100 μM) did not affect the vasodilator responses to puerarin, daidzein and daidzin, but glibenclamide (1 μM), tetraethylammonium (TEA, 100 mM) or a combination of K⁺ channel inhibitors (100 nM iberiotoxin + 1 mM 4-aminopyridine + 100 μM barium chloride + 1 μM glibenclamide + 100 mM TEA) reduced their I_max. The contractile response to CaCl₂ was attenuated by 61% and 34% in the presence of daidzein and daidzin, respectively, whereas, puerarin did not significantly affect the contraction.

Conclusions

The vasorelaxant action of daidzein and daidzin involved opening of K⁺ channels and inhibition of Ca²⁺ influx in the vascular smooth muscle cells. There is no evidence supporting involvement of endothelium-derived relaxing factors (EDRFs) in their actions. In contrast, puerarin produced vasodilatation via an endothelium-dependent mechanism involving nitric oxide production and an endothelium-independent pathway mediated by the opening of K⁺ channels. The cerebral vasodilator activities of all these three isoflavonoids may be beneficial to patients with obstructive cerebrovascular diseases.     

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.     

杜仲木脂素化合物舒张血管作用机制

目的：观察杜仲木脂素部位（EUL）对血管的舒张作用并探讨其机制。方法：以大鼠胸主动脉为标本,观察EUL对NE,KCl预收缩血管的舒张作用及对血管内皮细胞、血管平滑肌作用的影响。结果：EUL能显著舒张NE预收缩的血管,内皮去除后,该作用明显降低；KCl收缩下,EUL对主动脉环无明显舒张作用。去内皮的血管,EUL对NE在无Ca²⁺ 液中收缩幅度没有影响；使NE的量效曲线非平行右移,最大反应降低。钾通道阻断剂格列本脲孵育后能明显抑制EUL的舒血管作用。结论：杜仲木脂素部位有明显的舒血管作用,其机制与内皮依赖性有关。同时ATP敏感性K⁺ 通道也参与了EUL的舒血管作用。