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Indian Journal of Pharmacology, Vol. 37, No. 2, March-April, 2005, pp. 111-115 Research Paper Relaxant effect of Cuminum cyminum on guinea pig tracheal chains and its possible mechanism(s) Boskabady M.H., Kiani S., Azizi H. Deptartment of Physiology, Ghaem Medical Centre, Mashhad University of Medical Sciences, Mashhad Code Number: ph05020 ABSTRACT OBJECTIVE: To examine the relaxant effects of the macerated and aqueous extracts of Cuminum cyminum on the tracheal chains of guinea pig.MATERIALS AND METHODS: The relaxant effects of cumulative concentrations of macerated and aqueous extracts (0.25, 0.5, 0.75 and 1.0 g%) in comparison with saline and theophylline (0.25, 0.5, 0.75, and 1.0 mM) were examined on pre-contracted tracheal chains of guinea pigs under different conditions. RESULTS: In Group 1 experiments (contracted by KCl) only the last two concentrations of theophylline and the highest concentration of macerated extract showed significant relaxant effect compared to that of saline (P<0.001 and P<0.05 for theophylline and macerated extract respectively). The effects of the last two concentrations of theophylline in this group were significantly greater than those of the macerated and aqueous extracts (P<0.001). However, in Group 2 experiments (contracted by methacholine) both the extracts and theophylline showed concentration-dependent relaxant effect compared to that of saline (P<0.05 to P<0.001). The effects of the two last concentrations of both extracts were significantly lower than those of theophylline in Group 2 experiments (P<0.05 to P<0.001). In Group 3 (non-incubated, contracted by methacholine) the extracts of Cuminum cyminum did not show any relaxant effect of tracheal chains. The relaxant effects of macerated and aqueous extracts in Groups 1 and 3 were significantly lower than those of Group 2 (P<0.05 to P<0.001). However, the effects of different concentrations of theophylline obtained in Group 1 and 2 were not significantly different. There was a significant correlation between the effects and concentrations of theophylline in Groups 1 and 2, macerated extract in Groups 2 and 3 and aqueous extract in Group 1 (P<0.05 to P<0.001). CONCLUSION: These results show a potent relaxant effect of Cuminum cyminum on guinea pig tracheal chains which may be due to a stimulatory effect of the plant on β-adrenoceptors and/or an inhibitory effect on histamine H1 receptors. INTRODUCTION Cuminum cyminum was collected from the School of Pharmacy and identified by Mr. Ahei. A voucher specimen was preserved in the Herbarium of the School of Pharmacy, Mashhad University of Medical Sciences, Mashhad, Iran. Two types of extracts were prepared, Extract A with 50 g dried plant in 300 ml distilled water by soxhlet method and Extract B with the same amount of macerated plant in 300 ml distilled water on a shaker for 48 h. The solvent was removed under reduced pressure and distilled water was added so that the final plant ingredient concentration was 10 w/v in both extracts. Tissue preparations Male Dunkin-Hartly guinea pigs (400-700 g) were killed by a blow on the neck and tracheas were removed. Each trachea was cut into rings, 2-3 mm in length. All the rings were then cut open opposite to the trachealis muscle, and sutured together to form a tracheal chain.[13] The tissue was then suspended in a 10 ml organ bath (organ bath 61300, BioScience Palmer-Washington, Sheerness, Kent U.K.) containing Krebs-Henseliet solution (composition in mM: NaCl 120, NaHCO3 25, MgSO4 0.5, KH2PO4 1.2, KCl 4.72, CaCl2 2.5 and dextrose 11). The Krebs solution was maintained at 37ºC and gassed with 95% O2 and 5% CO2. Tissue was suspended under an isotonic tension of 1 g and allowed to equilibrate for at least 1 h with change of fresh Krebs solution every 15 min. The relaxant effects of four cumulative concentrations of extracts (0.25, 0.5, 0.75, and 1.0 w/v), theophylline anhydrous (Sigma Chemical Ltd., UK) (0.25, 0.5, 0.75, and 1.0 mM), and 1 ml saline as control were examined. To produce different concentrations of macerated and aqueous extracts, 0.25 ml of 10g % extracts were added to a 10 ml organ bath four times. For theophylline, 0.25 ml of 10 mM solution was added to an organ bath four times. The consecutive volumes were added to the organ bath at five minute intervals. In each experiment the effect of four cumulative concentrations from each extract, theophylline, or 1 ml saline on contracted tracheal smooth muscle was measured. A decrease in tone was considered as a relaxant (bronchodilatory) effect and expressed as positive percentage change in proportion to the maximum contraction, and an increase in tone was considered as a contractile (bronchoconstriction) effect, which was expressed as negative percentage change.[14] The relaxant effect of the different solutions was tested with three different experimental designs as follows:
Statistical analysis All data were expressed as mean±SEM. Data of the relaxant effects of different concentrations of the extracts were compared with the results of negative and positive control using one-way ANOVA with Tukey-Kramer post-test. The data of the relaxant effect obtained in three groups of experiments were also compared using the same statistical method. The relaxant effect of the two extracts and theophylline were related to the concentrations, using least square regression. Significance was accepted at P< 0.05. RESULTS Relaxant (bronchodilatory) effect The relaxant effect of both extracts and theophylline were concentration-dependent. There was a significant relationship between the concentrations and response of theophylline in Groups 1 and 2, macerated extract in Groups 2 and 3 and aqueous extract in Group 2 (P< 0.05 to P< 0.001). The relaxant effects of all concentrations of the macerated extract were greater than those of the aqueous extract in all groups of experiments. The effects of the macerated and aqueous extract at many concentration levels in Groups 1 and 2 of experiments were lower than those of theophylline. The relaxant effect of different extracts from Cuminum cyminum on tracheal chains of guinea pigs might be due to several different mechanisms including stimulation of β-adrenergic receptors, inhibition of histamine H1 receptors or an anticholinergic property of this plant, because the relaxant effect of β2-stimulatory,[14],[15] histamine H1 receptor inhibitory,[16] and anticholinergic drugs [17] have been shown in previous studies. To evaluate the contribution of the β-adrenergic stimulatory and/or H1 histamine blocking effect of the macerated and aqueous extracts from this plant to their bronchodilatory effects, the effects of these extracts on tracheal chains were examined in presence of propranolol and chlorpheniramine respectively. The relaxant effects of most concentrations of both extracts from Cuminum cyminum obtained in Group 3 experiments were significantly lower than those of Group 2. These findings suggest probable β-adrenergic stimulatory and/or histamine H1 blocking properties of the plant extracts that may contribute to their relaxant effect on tracheal chains. The absence of the obvious relaxant effect of the aqueous extract from Cuminum cyminum in Group 1 and the its relatively potent relaxant effect in Group 2 experiments may be due to potassium channels opening which has been demonstrated to produce bronchodilation.[18] If this extract from Cuminum cyminum had a potassium channel opening effect, it would not have a relaxant effect on tracheal chains contracted by KCl, while it could show relaxant effect when the tracheal chain was contracted by methacholine. It has been shown that KCl affects calcium channels[19] and calcium channel blockers have bronchodilatory effect.[20],[21] Therefore, the relaxant effect of macerated extract in Group 1 may indicate an inhibitory effect of this extract on calcium channels. The effects of different concentrations of the macerated extract in all groups of experiments were greater than those of the aqueous extract. These results may suggest that the effective substances causing a relaxant effect on guinea pig tracheal chains are higher in the macerated extract than the aqueous extract. Although both the macerated and aqueous extracts are aqueous in nature, the differences in the effect of these two extracts could be due to the variation in their constituents due to the method of extraction. With regard to the airway inflammation of asthmatic and COPD patients, Cuminum cyminum might also have an antiinflammatory effect, which will contribute to the therapeutic effect of this plant on asthma and COPD. In fact, the antiinflammatory effect of this plant has been reported.[9] However, the effect of Cuminum cyminum on airway inflammation needs further investigation. In conclusion the results of this study indicate a relatively potent relaxant (bronchodilatory) effect of Cuminum cyminum on the tracheal chains of guinea pigs. A stimulatory effect of the plant on β-adrenoceptors and/or an inhibitory effect on histamine H1 receptors are suggested as the possible mechanisms, apart from the opening of potassium channels and inhibition of calcium channels. ACKNOWLEDGEMENT This study was financially supported by the Vice Presidency of Research of Mashhad University of Medical sciences. REFERENCES
Copyright 2005 - Indian Journal of Pharmacology The following images related to this document are available:Photo images[ph05020f1.jpg] [ph05020t2.jpg] [ph05020t1.jpg] |
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