Effects of extracts of Portulaca oleracea on skeletal muscle in vitro

Extracts of Portulaca oleracea inhibited twitch tension due to direct (MS) and indirect electrical stimulation via the phrenic nerve (NS) of the rat hemidiaphragm muscle. The rank order of potency was dialysable extract greater than or equal to methanol extract greater than diethylether extract, although all exhibited equal efficacy. The non-dialysable extract did not inhibit twitch tension due to MS or NS. The dialysable, methanol and diethylether extracts inhibited tetanus tension, and attenuated the area under the K+- and caffeine-induced contracture. The contracture induced by nicotinic agonists and K+ on the rectus abdominis muscle was significantly inhibited by these extracts.     

Effects of stembark and leaf extracts of Bridelia ferruginea on skeletal muscle

The ethanolic extracts of the leaves and stembark of Bridelia ferruginea were separately investigated for their effects on skeletal muscle using the phrenic nerve-hemidiaphragm muscle preparation from rats. The bark extract inhibited twitch tension induced by direct electrical stimulation (muscle) (MS) but not indirect electrical stimulation (nerve) (NS) of the diaphragm. It inhibited tetanus tension to both nerve (TNS) and muscle stimulation (TMS), had no effect on K⁺-induced contracture and reduced the minimal fusion frequency (MFF). The leaf extract had no effect on twitch tension to NS and MS or K⁺-induced contracture but increased tetanus tension to TNS or TMS as well as MFF. These findings suggest that the bark extract does not affect influx of extracellular Ca²⁺ but inhibits the intracellular mobilization of Ca²⁺. The leaf extract also had no effect on influx of extracellular Ca²⁺ but most likely facilitated the intracellular mobilization of Ca²⁺. Thus, the intracellular action of the bark extract is opposite to that of the leaf extract.     

Comparison of the skeletal muscle relaxant properties of Portulaca oleracea extracts with dantrolene sodium and methoxyverapamil

The effects of aqueous (AEE), dialysable (DIF) and methanol (MEE) extracts of Portulaca oleracea stems and leaves were compared with those of dantrolene sodium and methoxyverapamil (D-600) with respect to inhibition of twitch tension on the rat phrenic nerve-hemidiaphragm and with respect to contracture induced by nicotinic agonists on the frog rectus abdominis preparations. The extracts, dantrolene and D-600 inhibited twitch tension due to indirect electrical stimulation via the phrenic nerve (NS) on hemidiaphragm muscle, whereas the extracts and dantrolene inhibited, in addition, twitch amplitude due to direct muscle stimulation (MS). The extracts, dantrolene and D-600 also attenuated K+- and caffeine-induced contractures with the extracts and D-600 also reducing the time taken for the K+-induced contracture to fall to basal tension. In addition, the tetanic tension due to NS and MS was attenuated with only the extracts and dantrolene reducing the twitch/tetanus ratio (MS). There was a non-significant but consistent tendency for mutual potentiation between the extracts and dantrolene with respect to their inhibitory effect on twitch amplitude (MS) resulting in a shift to the left of the concentration-response curves to the extracts or dantrolene. This was not evident with the extracts and D-600 or dantrolene and D-600. Simultaneous addition of the extracts and dantrolene resulted in an increase in the rate of twitch tension inhibition and a decrease in the time to maximum relaxation of twitch amplitude (MS). The extracts and D-600 proved more effective in attenuating nicotinic agonist (acetylcholine, carbachol and nicotine)-induced contractures on the rectus abdominis muscle than dantrolene. From these observations, it appears that the Portulaca oleracea extracts mimic, in part, the effect of D-600 and dantrolene on the rat hemidiaphragm and frog rectus abdominis muscles; therefore, the muscle relaxant properties of the extracts may be due, in part, to inhibition of trans-membrane Ca influx, interference with the Ca-induced Ca release process and/or inhibition of the release of intracellular Ca from stores in the sarcoplasmic reticulum.     

人参皂甙对大鼠输精管和肛尾肌中α受体效应的影响

人参皂甙(G,10~(-4)g/ml)对离体大鼠输精管(RVD)的正常张力无影响,但能增强电场刺激引起的RVD收缩效应,对抗可乐定(Clo)抑制和育亨宾(Yoh)增强电场刺激引起的RVD收缩。G使苯福林(Phe)对RVD和肛尾肌(RAM)α_1受体作用的量效曲线右移。上述结果进一步支持G在突触前后膜α受体水平上可能均起着调谐剂(modulator)样作用的观点。     

Some neuromuscular effects of the crude extracts of the leaves of Abrus precatorius

Some neuromuscular effects of the crude extracts of the leaves of Abrus precatorius were investigated using isolated toad rectus abdominis and rat phrenic nerve-diaphragm muscle preparations as well as young chicks. The ethanol extract of the leaves inhibited acetylcholine-induced contractions of both toad rectus abdominis and rat phrenic nerve-diaphragm muscle preparations. The effects were concentration-dependent and reversible. The extract also caused flaccid paralysis when injected intravenously into young chicks. The ethanol extract had no effect on direct electrical stimulation of rat diaphragm. The inhibitory effect of the ethanol extract on the rat phrenic nerve-diaphragm preparation was potentiated in the presence of reduced calcium ions, elevated magnesium ions, or reduced potassium ions. Thus, the ethanol extract showed a similarity to d-tubocurarine in respect of the pattern of neuromuscular blockade. Both the petroleum ether and the water (cold and hot) extracts had no observable effects on the skeletal muscles used in this project. Apparently, the poisonous neuronal component of the leaves of Abrus precatorius resides mainly in the ethanol extract.     

Effects of veratrine and paeoniflorin on the isolated rat aorta.

The interactions and mechanisms between veratrine and paeoniflorin on the isolated rat aorta were studied. Veratrine (1x10(-6) to 1x10(-4) g/ml) could induce contraction on the isolated rat aorta in a concentration-related manner. Paeoniflorin had no effect on the isolated rat aorta. Pretreatment with prazosin (1x10(-6) M) and nifedipine (1x10(-6) M) but not yohimbine (1x10(-5) M) could decrease the tension of contraction induced by veratrine (1x10(-4) g/ml). Sodium nitroprusside (1x10(-4) M) could inhibit the contraction induced by veratrine (1x10(-4) g/ml) with or without endothelium, whereas methylene blue (5x10(-5) M) could increase the contraction induced by veratrine (1x10(-4) g/ml). Treatment with veratrine (1x10(-4) g/ml) could decrease the tension of contraction induced by norepinephrine (1x10(-6) M) or phenylephrine (1x10(-4) M). The inhibition of veratrine on norepinephrine-induced contraction was potentiated by L-arginine (1x10(-4) M) and reversed by L-NAME (1x10(-5) M). Paeoniflorin (1x10(-4) M) could decrease the tension of contraction induced by veratrine (1x10(-4) g/ml) and methylene blue (5x10(-5) M). The inhibition of paeoniflorin on veratrine was more potent on rat isolated aorta with endothelium than without endothelium. Ryanodine (1x10(-5) M) and Ca2+ -free medium could inhibit methylene blue-induced contraction. From the above results, the relaxation of veratrine on the norepinephrine-induced contraction might be related to the increase of NO and cGMP. The contraction of veratrine on the isolated rat aorta was via the increase of intracellular calcium which was inhibited by paeoniflorin.     

Neuromuscular effects and acute toxicity of an ethyl acetate extract of Spigelia anthelmia Linn

An ethyl acetate extract of Spigelia anthelmia (EASa), with validated anthelmintic activity, was evaluated for its acute toxicity and general effects in albino Swiss mice and for neuromuscular relaxant activity in the frog sciatic-gastrocnemius and rectus abdominis preparation. The extract induced a dose-related myotonia and muscular paralysis of rapid onset at higher doses. The calculated LD50 after oral and intraperitoneal administration was 345.9 [241.4-484.7] mg/kg and 60.8 [47.4-80] mg/kg, respectively. In broilers, intramuscular injection of EASa-induced spastic paralysis qualitatively similar to that obtained after succinylcholine administration and contrasting to the flaccid paralysis induced by D-tubocurarine. The contraction elicited by direct stimulation of the gastrocnemius was blocked by EASa by 54.3+/-4.7% (IC50 = 21.4 [11.2-35.8] microg/ml) and the twitches evoked by stimulation of the sciatic nerve were blocked by 69.1+/-7.4% (IC50 = 17.9 [4.5-34.23] microg/ml). EASa also blocked acetylcholine-induced contractions in the frog rectus abdominis by 58.6+/-7.4% (IC50 = 7.4 [1.7-15.28] microg/ml) but did not decrease tonic contractions induced by a high-potassium Ringer solution. In summary, the ethyl acetate extract of Spigelia anthelmia induces tonic paralysis in vivo, and decreases amplitudes of twitches and increases tonus of skeletal muscle in vitro.     

The relaxant activity of the methanolic extract of Acanthus montanus on intestinal smooth muscles

The effects of the methanolic extract of Acanthus montanus on different smooth muscle preparations have been investigated. The extract (6.25-100 microg/ml) produced a concentration-dependent relaxation and inhibition of the spontaneous contraction of the rabbit jejunum which was reversed by CaCl2 (0.1-1mM). This effect of the extract was not blocked by propranolol (3 x 10(-7) M) but partially antagonised by phentolamine (10(-6)-3 x 10(-6) M), procaine (10(-3) M) and methylene blue (10(-5) M). The extract also caused a concentration-dependent relaxation of the KCl-precontracted taenia coli of the guinea-pig which was partially blocked by propranolol (3 x 10(-5) M) that completely blocked isoprenaline (10(-8)-3 x 10(-4) M) relaxation of the tissue. Methylene blue (10(-5) M) and procaine (10(-3) M) completely blocked the direct relaxant effects of the extract and isoprenaline on the guinea-pig taenia coli. The extract (0.1-1mg/ml) shifted the concentration-response curves of CaCl2 to the right in a concentration-dependent manner on the guinea-pig taenia coli. These effects of the extract suggest a non specific smooth muscle relaxant activity.     

Isolation and pharmacological characterization of vernolepin

Vernolepin, a sesquiterpene lactone, was isolated from the dried fruit of Vernonia amygdalina Del. The different steps used during the extraction were: continuous extraction with chloroform, partition of the chloroform-extract between pertroleum ether and 10% aqueous methanol, column chromatography of the methanol extract, isolation of the active fractions by pharmacological and chemical characterization. Vernolepine was obtained as colorless prisms and identified by melting point, uv, ir, 1H nmr, optical rotation, and mass spectrometry. The total content of the dried fruit was 0.09% vernolepin. The first pharmacological characterization of vernolepin revealed: (1) a competitive antagonism against histamine in guinea pig ileum (pA2 = 5.61; 15 min incubation); (2) a biphasic enhancement/inhibition of coaxial stimulation of guinea pig ileum; (3) an antiaggregating and disaggregating activity against rabbit platelet aggregation induced by arachidonic acid (1 X 10(-4) g/ml; 3.3 X 10(-4)M) or ADP (4 X 10(-6) g/ml; 1 X 10(-5)M) without inhibition of cyclo-oxygenase or lipoxygenase. All these reactions were time dependent and occurred at concentrations of 5 X 10(-6) to 1 X 10(-5) g/ml vernolepin (1.8 to 3.5 X 10(-5)M).     

Phytochemical and pharmacological investigation of the cardioactive constituents of the leaf of Dysoxylum lenticellare

The cardiac effects of the leaf extract and 11 isolated pure compounds have been examined on isolated, spontaneously beating, atrial muscles of the rat. Using nor-adrenaline (8 X 10(-7)M) and acetylcholine (4 X 10(-8)M) as reference drugs and normal saline (equivalent volume) as control, the crude extract of Dysoxylum lenticellare (8 X 10(-4) g/ml) induced negative chronotropic and positive inotropic responses on the isolated cardiac muscle preparations. The extract demonstrated significant (p less than 0.05-0.01) cardioactivity as attested to by its positive inotropic and/or negative chronotropic activities on the rat atrial preparations. Of the pure isolates tested, 7, 8, and 9 demonstrated significant cardiac effects. Although the precise mechanism of action of the extract or pure isolates on the atrial myocardium has not been fully determined, available experimental data suggest that the extract and pure isolates act directly on the cardiac muscle. Alkaloids 7, 8, and 9 manifest cardiac effects similar to that of the crude extract but of lesser magnitude. Some indirect effects of these isolates may, however, be associated with the manifested activities.     

Effects of extracts of seed and leaf of Piper guineense on skeletal muscle activity in rat and frog

The pharmacological effects of leaf and seed extracts of Piper guineense were investigated on phrenic nerve hemidiaphragm activity following electrical stimulation in vitro. The Leaf and seed extracts (10 micrograms-1 mg/mL) and (50-800 micrograms/mL) respectively produced biphasic effects consisting of an initial enhancement followed by secondary transient or prolonged depression of twitch tension in response to electrical stimulation of both muscle and nerve. These effects were similar to that of decamethonium (2-800 mg/mL). An increased concentration of extracellular Ca2+ in vitro reversed the twitch contraction inhibited by the leaf and seed extracts in a dose related pattern following electrical stimulation. It is concluded that the leaf and seed extracts of Piper guineense possess among other pharmacological properties, a depolarizing neuromuscular blocking action.     

Effects of Olax gambecola methanol extract on smooth muscle and rat blood pressure

A methanol extract of the roots of Olax gambecola induced a biphasic contractile response consisting of a transitory initial rapid contraction (Phase I), followed by a slowly developing sustained increase in basal tone (Phase II) on rat fundus, antrum, guinea pig taenia coli, rabbit jejunum and aorta. The Phase I contraction was abolished by atropine, attenuated significantly by indomethacin and potentiated by physostigmine while the Phase II response was unaffected. Hexamethonium, morphine, serotonin (5-HT) antagonists or desensitization of 5-HT receptors did not alter either the Phase I or the Phase II contractions. Calcium channel blockers and procedures affecting calcium translocation abolished the Phase I contraction while only reducing the Phase II contractions. Transmural electrical stimulation produced contractions of the fundus which were attenuated by the extract. Single bolus injections of extract produced a rapid fall in blood pressure in both normotensive and spontaneously hypertensive rats but intravenous infusion resulted in a sustained fall in blood pressure which was maintained throughout the infusion period. Chronic i.p. administration of extract to spontaneously hypertensive rats reduced blood pressure markedly but did not alter the blood pressure of normotensive animals. The hypotensive response to single bolus injections was abolished by atropine and potentiated by physostigmine. The activity profile of the extract suggests the presence of at least two active principles in the crude extract of Olax gambecola used in this study.     

Phytochemical screening and effect of aqueous extract of Ficus sycomorus L. (Moraceae) stembark on muscular activity in laboratory animals

The stembark of Ficus sycomorus was collected, dried and extracted, to screen for some chemical constituents and study its effect on muscle contraction. The duodena and recti abdominis of 10 guinea pigs weighing between 330 and 345 g and 10 frogs weighing between 180 and 201 g, respectively, were isolated and used for this study. The extract was tested to see its effect on acetylcholine (ACH) induced contraction on kymograph. The extract reduced the acetylcholine contractile responses of guinea pigs duodena and recti abdominis muscles of frogs significantly, thus showing inhibitory effect on muscle contraction. The extract showed the presence of gallic tannins, saponins, reducing sugars, alkaloids and flavone aglycones. It was concluded that the extract has inhibitory effect on both smooth and skeletal muscles contractions and contains important constituents for pharmacological activities.     

胚胎肢芽提取液对失神经肌肉的作用

目的:本实验用大鼠胚胎肢芽为材料,提取生物活性物质,研究其对失神经支配肌肉的保护作用,以期为胚胎肢芽营养蛋白有效成分的研究提供依据,探索延缓失神经肌肉萎缩的方法和途径。方法:切除大鼠右侧坐骨神经0.5cm,缝合伤口。实验组采用生物化学方法提取的胚胎肢芽中营养蛋白(embryoniclimbbudextract,ELBE)0.1ml/天(1mg/ml)注射至失神经支配的趾长伸肌中,对照组注射生理盐水0.1ml/天。分别于术后7天、14天两时间段取材,进行肌张力、肌湿重,总蛋白含量和肌纤维横截面积测定。结果:失神经支配趾长伸肌应用ELBE后7天、14天时,单收缩力和强直收缩力均较对照组增加(30%~60%)(P<0.05),肌湿重和蛋白含量下降减慢率在7天时,实验组优于对照组,两者差异有显著性意义(P<0.05)。14天时,实验组明显高于对照组,两者差异有显著性意义(P<0.01,P<0.05)。7天、14天时实验组的肌纤维截面积均较对照组增多(P<0.05)。结论:胚胎肢芽提取液(ELBE)可减缓失神经肌肉的萎缩。除了已知的其对神经营养作用外,ELBE具有减少失神经肌肉形态和功能改变的肌营养作用。     

Spasmogenic effect of a Solanummelongena leaf extract on guinea pig tracheal chains and its possible mechanism(s)

The methanol extract of fresh leaves of Solanum melongena L. (Solanaceae) was evaluated for its capacity to alter the tone of isolated, pre-contracted guinea pig tracheal chains, as well as for its possible mechanism(s) of action. Using serial dilutions between 0.0025 and 2.5 mg/mL, the extract was found to cause a dose-dependent increase in the force of muscle contraction. The EC(50) value was 0.46 +/- 0.01 mg/mL. The concomitant use of acetylcholine 10(-5) M did not significantly affect the force of contraction induced by the extract. Histamine 10(-5) M added at about 40% to, and salbutamol 10(-6) M antagonized by about 30% its constrictive effect. Chlorpheniramine 10(-6) M, propanolol 10(-5) M, and nifedipine 10(-6) M did not significantly influence the extract-induced force of contraction, but atropine 3 x 10(-7) M reduced it by approximately 60%. These data suggest that the Solanum melongena extract exerted a bronchospasmogenic rather than a bronchospasmolytic effect, probably through muscarinic receptor stimulation.     

Pharmacological effects of Synclisia scabrida alkaloid B on some isolated muscle preparations

Alkaloid B reversibly blocked the responses of rat diaphragm to electrically induced stimulations via the phrenic nerve. The alkaloid had no effect on the responses of the diaphragm elicited by direct electrical stimulation. The responses of frog rectus abdominis muscle to acetylcholine were inhibited by alkaloid B.Alkaloid B reversibly antagonised the responses of rabbit duodenum to exogenously applied acetylcholine. The contractile effect of oxytocin on rat uterus was specifically inhibited by alkaloid B. The effects of alkaloid B on isolated muscle preparations were concentration-dependent. However, the effect of dopamine and noradrenaline on rat vas deferens was not altered by alkaloid B.     

The interactions of paeoniflorin and veratrine on isolated rat atria

In this study, we attemped to identify the interactions and mechanisms between veratrine and paeoniflorin on isolated rat atria. Paeoniflorin alone showed no effect on the rat atria. Veratrine increased the atrial contraction and induced arrhythmia at 1×10⁻⁵ g/ml. Veratrine could directly induce contraction and elicit tetanic contraction at 1×10⁻⁴ g/ml in the left atria with or without electric stimulation. Paeoniflorin (4.8×10⁻⁶ to 4.8×10⁻³ g/ml), verapamil (2.2×10⁻⁶ g/ml), tetrodotoxin (TTX) (3.2×10⁻⁸ g/ml) and quinidine (7.5×10⁻⁶ g/ml) inhibited the increase of contraction and delayed the onset of contraction induced by veratrine (1×10⁻⁵ g/ml). The inhibitory effect of paeoniflorin combined with verapamil on the contraction induced by veratrine was more potent than that of paeoniflorin or verapamil alone. However, the inhibitory effect of paeoniflorin was not potentiated by TTX or quinidine. From the above results, the contraction evoked by veratrine in the rat atria may be concluded to be caused by the stimulation of Na⁺- and Ca²⁺-ion channels. The inhibition of paeoniflorin on the contraction induced by veratrine may primarily be related to the blockade of Ca²⁺ channels.     

Mechanisms of relaxant action of a crude hexane extract of Gnaphalium liebmannii in guinea pig tracheal smooth muscle

We investigated the mechanisms of action of Gnaphalium liebmannii which is used as a folk medicine in México for treating various respiratory diseases such as gripe, fever, asthma, cough, cold, bronchitis, expectorating, and bronchial affections. The tension changes of guinea pig tracheal segments were isometrically recorder on a polygraph. Hexane extract of Gnaphalium liebmannii was the most active relaxant extract (IC(30)=54.23+/-19.79 microg/mL with 99.5+/-3.2 % of relaxation), followed by dichloromethane extract (IC(30)=120.22+/-5.27 microg/mL) and methanol extract (IC(30)=190.25+/-30.02 microg/mL). Hexane extract produced a parallel rightward shift of the concentration-response curve of carbachol in a competitive manner (pA(2)=-2.4), but did not modify the concentration-response curves for histamine. The relaxant effect of hexane extract of Gnaphalium liebmannii was unaffected by the presence of propranolol (3x10(-6)M) or glibenclamide (10 microM). However hexane extract produced a leftward shifts of the concentration-response curve of forskolin (10(-8) to 10(-3)M), nitroprusside (10(-10) to 10(-6)M), isoproterenol (3x10(-10) to 3x10(-5)M) and aminophylline (10(-11) to 10(-2)M). The above results suggest that Gnaphalium liebmannii induce relaxation of the tracheal muscle, probably via phosphodiesterase inhibition. The bronchodilator effect of Gnaphalium liebmannii might explain in part their traditional use as anti-asthmatic remedy.     

Pharmacological effects of Eugenia punicifolia (Myrtaceae) in cholinergic nicotinic neurotransmission

The effects of the aqueous crude extract (5%) of Eugenia punicifolia on cholinergic nicotinic neurotransmission were investigated. Actions of aqueous crude extract over the inhibitory effect of the cholinergic nicotinic antagonists gallamine or pancuronium, on contractions induced by electrical stimulation of phrenic nerve of rat diaphragm, were studied. Tissues were mounted as for isotonic contractions and stimulation was delivered at submaximal voltage. Addition of Eugenia punicifolia did not alter the amplitude of twitch contraction. Gallamine (IC(50): 28.8+/-0.51 microM) or pancuronium (IC(50): 3.16+/-0.11 microM) completely inhibited twitch contractions. After the maximum effect of the antagonists was achieved, addition of the aqueous crude extract (0.5-1.0 mL) totally recovered the responses to electrical stimulation. Neostigmine, a reversible acethylcholinesterase inhibitor, partially recovered responses (49.70+/-6.90% at 1 microM). In another series of experiments, previous incubation of the extract (0.5 mL) shifted to the right inhibitory concentration-response curves for the antagonists gallamine (IC(50) before E. punicifolia: 35.8+/-1.61 microM; IC(50), after E. punicifolia: 2.24+/-0.04 mM) and pancuronium (IC(50), before E. punicifolia: 3.55+/-0.13 microM; IC(50), after E. punicifolia: 0.39+/-0.01 mM). Our results show that the aqueous extract of E. punicifolia recovered the action of competitive nicotinic antagonists at the neuromuscular junction. A receptor-mediated mechanism or the possibilities of interactions of the extract with the enzyme acethylcholinesterase, however, remain to be investigated.     

Neurosedative and muscle-relaxant activities of ethyl acetate extract of Baphia nitida AFZEL

The sedative, anxiolytic and muscle-relaxant effects of the ethyl acetate leaf extract of Baphia nitida (BN) was investigated in intact mice, using the hole-board head-dip test for exploratory behavioural effect, elevated plus maze (EPM) and Y-maze (YM) models of anxiety; chimney, inclined screen, traction and climbing tests for muscle-relaxant effects. In each of these tests, BN (100-400mg/kg, p.o.), diazepam (1mg/kg, i.p.) or distilled water (10ml/kg, p.o.) was administered, 30 or 60min before performing the tests in mice. For exploratory behavioural test, number of head-dip within 15min was counted. For EPM and YM tests, the cumulative time spent in open and closed arms was recorded within 5min. In the muscle-relaxant tests, mice were subjected to modified models such as chimney, inclined screen, traction and climbing tests. BN produced a significant (P<0.05) dose-related decrease in exploratory behaviour in the head-dip test and prolongation of cumulative time spent in open arms of both EPM and YM. BN did not show any significant effect in the chimney and traction tests, but produced significant, dose-dependent muscle relaxation in the inclined screen and climbing tests. Furthermore, BN (200-1200microg/ml) non-competitively shifted the curves of acetylcholine contractions of the toad Rectus abdominis muscle to the right. Oral doses of BN (0.1-20g/kg) did not produce mortality, but the LD(50) when given intraperitoneally, was 645.65mg/kg. Results suggest that the leaf extract of Baphia nitida has sedative, anxiolytic and skeletal muscle-relaxant effects and support its neurosedative use in traditional African medicine.