1. In vitro studies of non-specific histidine decarboxylase activity was low or absent in control guinea-pigs and unchanged 9 or 27 hr after chlorpromazine (CPZ) injection intraperitoneally. 2. However, specific histidine decarboxylase activity was found in the control tissues and was increased 9 hr but not 27 hr after CPZ injection.
Vietnamese coriander (Polygonum odoratum Lour.) is a plant native to northern Thailand. The biological activities of P. odoratum Lour. extract (POE) include antibacterial, antiviral, and expectorant. However, the effect of POE on intestinal smooth muscle motility is unclear. The aim of this study was to evaluate the relaxant effects of POE on isolated rat ileum. Propranolol (1 μM), calcium chloride (1-20 mM), and Nω-nitro-l-arginine methylester (l-NAME, 100 μM) were used to investigate the mechanisms of action. The results showed that POE (0.01-5 mg/mL) reduced KCl-induced contraction. In addition, POE (1 mg/mL) reduced the contraction by propranolol and l-NAME and attenuated CaCl2-induced contractions. Our results indicate that the relaxation effect of POE on ileum contractions seems to involve nitric oxide and β-adrenergic pathways, and blockade of calcium influx. These findings provide a pharmacological basis for the traditional use of POE to treat gastrointestinal disorders such as irritable bowel syndrome or diarrhea.
This study aimed to elucidate the mechanism(s) of the spasmogenic action of Loranthus ferrugineus in isolated guinea pig ileum. Thus the contractile responses of guinea pig ileum to graded additions of either L. ferrugineus methanol extract or its n-butanol fraction were tested in the presence and absence of various pharmacological interventions. The data showed that L. ferrugineus methanol extract and the n-butanol fraction produced a concentration-dependent spasmogenic effect in isolated guinea pig ileum segments. These effects were significantly inhibited in the presence of 1 microM atropine. In contrast, the response to the lowest concentrations of L. ferrugineus methanol extract (0.25, 0.5 and 1 mg/mL) and n-butanol fraction of L. ferrugineus (0.125, 0.25 and 0.5 mg/mL) were considerably enhanced in the presence of 0.05 microM neostigmine. Neither L. ferrugineus methanol extract nor n-butanol fraction contractile responses were affected upon the incubation of the ileal segments with 100 microM hexamethonium. The results of this study show that the spasmogenic effect of L. ferrugineus is possibly mediated through a direct action on intestinal muscarinic receptors. It is suggested that the bioactive constituents of L. ferrugineus serve as a substrate for acetylcholinesterase.
1. Oral administration of [14C]histamine induced the presence of small amounts of [14C]histamine in stomach and ileal tissues of control guinea-pigs. In contrast, much larger amounts were found after 8 h infusion. 2. Similar amounts of [14C]histamine were found in the tissues when [14C]histamine was given by intravenous infusion from 24-30 h after chlorpromazine injection.
The electrically stimulated guinea-pig ileum and spontaneously contracting guinea-pig ileum preparations were employed in studies on the effects of an alcoholic extract and two flavonoid compounds, quercetin and quercetin-3-arabinoside, extracted from the leaves of Psidium guajava. The extract showed a morphine-like inhibition of acetylcholine release in the coaxially stimulated ileum, together with an initial increase in muscular tone, followed by a gradual decrease. The morphine-like inhibition was found to be due to quercetin, starting at concentrations of 1.6 micrograms/ml. The glycoside did not show any such action at concentrations of up to 1.28 mg/ml. The extract inhibited spontaneous contractions in the unstimulated ileum with a concentration-response relationship.
The effect of the total glysosidic extract of the plant Sarcolobus globosus was investigated on the contractions of the smooth muscle of the guinea-pig ileal longitudinal muscle and taenia coli. In the ileal longitudinal muscle, addition of the extract inhibited the electrical field-stimulated twitches. Similarly to verapamil, it also reduced the contractions of the muscle to acetylcholine, histamine and KCl. However, only the tonic contraction to KCl was reversed by increasing the extracellular calcium concentration. In the taenia coli, lower concentrations of both the extract and verapamil induced a parallel displacement of the dose-response curves to calcium (0.30-30 mM). Addition of the extract also dose-dependently inhibited the KCl-induced contraction of the taenia coli. Increasing the calcium concentration increased the IC50 values of the extract. The result suggests that the inhibitory effect of the Sarcolobus globosus extract on the smooth muscle, like verapamil, is mainly due to inhibition of calcium influx.
The present investigation was aimed at determining the effects of hexane, acetone, methanol and aqueous extracts of Acorus calamus leaves (ACHE, ACAE, ACME and ACAQE) on cholinergic and histaminic system using isolated frog rectus abdominis muscle and guinea pig ileum. A dose dependent potentiation of Ach response (anticholinesterase like effect) was found with ACAE and ACME at 0.25, 0.5, 0.75 and 1 mg/ml, but at higher dose of ACAE, ACME, ACAQE and ACHE (5, 20 mg/ml) inhibit the Ach response (antinicotinic effect). These results revealed biphasic effect of Acorus calamus leaves extracts on acetylcholine induced contractile response in isolated frog rectus abdominis muscle preparation (i.e. potentiation effect at lower dose and inhibitory effect at higher dose). Studies on isolated guinea pig ileum demonstrated antihistaminic effect in a dose dependent manner (100-1000 µg/ml) with ACAE, ACME and ACAQE. In addition, the dose dependent inhibition of Ach response (antimuscarinic effect) was observed with ACAE and ACME. In conclusion, Acorus calamus leaves extracts exerts antinicotinic, anticholinesterase like activities in isolated frog rectus abdominis muscle and antihistaminic, antimuscarinic effect in guinea pig ileum. It has been suggested that these observed activities can be further studied for therapeutic potential of Acorus calamus leaves in the treatment of cognitive disorders and asthma.
Cymbopogon citratus, commonly known as lemongrass, has been shown to have antioxidant, antimicrobial and chemo-protective properties. Citral, a monoterpenoid, is the major constituent of C. citratus that gives off a lemony scent and is postulated to be responsible for most of its actions. In addition, C. citratus has been traditionally used to treat gastrointestinal discomforts, however, the scientific evidence for this is still lacking. Thus, the aim of the present study was to investigate the effect of the extracts of various parts of C. citratus (leaves, stems and roots) and citral on the visceral smooth muscle activity of rabbit ileum. The effect of the test substances were tested on the spontaneous contraction, acetylcholine (ACh)- and KCl-induced contractions. Citral at doses between 0.061 mM to 15.6 mM and the extract of leaves at doses between 0.001 mg/mL to 1 mg/mL significantly reduced the spontaneous, ACh- and KCl-induced ileal contractions. When the ileum was incubated in K(+)-rich-Ca(2+)-free Tyrode's solution, it showed only minute contractions. However, the strength of contraction was increased with the addition of increasing concentrations of CaCl(2). The presence of citral almost abolished the effect of adding CaCl(2), while the leaf extract shifted the calcium concentration-response curve to the right, suggesting a calcium antagonistic effect. These results were similar to that elicited by verapamil, a known calcium channel blocker. In addition, the spasmolytic effect of citral was observed to be reduced by the nitric oxide synthase inhibitor, L-NAME. In conclusion, citral and the leaf extract of C. citratus exhibited spasmolytic activity and it appeared that they may act as calcium antagonists. Furthermore, the relaxant effect of citral, but not that of the leaf extract may be mediated by nitric oxide suggesting the presence of other chemical components in the leaf extract other than citral.
In the present study, L. ferrugineus methanol extract (LFME) was evaluated for its blood pressure lowering effect in anesthetized normotensive Sprague Dawley (SD) rats and its spasmogenic effect in isolated guinea pig ileum. The possible mechanism(s) of action were also investigated. LFME was obtained by Soxhlet extraction. The rats were fasted overnight and anesthetized with sodium pentobarbitone (60 mg/kg i.p.). LFME was administered in i.v. boluses in the concentrations of 25, 50, 100 and 200 mg/kg respectively, with concomitant monitoring of mean arterial pressure (MAP). It was found that LFME dose-dependently reduced MAP. An i.v. bolus injection of atropine significantly decreased the blood pressure lowering effect of LFME. Similarly, L-NAME (Nomega-nitro-L-arginine methyl ester) significantly lowered both the MAP and the action duration. Conversely, no significant change in MAP was seen following i.v. injections of neostigmine, hexamethonium, prazosin and propranolol. LFME also produced a dose-dependent contractile effect in guinea pig ileum. This contraction was significantly reduced in atropine pre-incubated tissue segments, yet it was significantly enhanced in the presence of neostigmine. No appreciable change in the ability of LFME to contract guinea pig ileum was seen in the presence of hexamethonium. Accordingly, it can be postulated that LFME possesses a marked hypotensive effect that can be attributed to stimulation of muscarinic receptors and/or stimulation of nitric oxide (NO) release. Moreover, LFME retains a considerable spasmogenic action due to its cholinergic properties. The hypotensive and spasmogenic effects of LFME justify its traditional uses.