| Abstract: | The hot water extract (HWE) of the seed of Mucuna pruriens dose-dependently contracted the guinea-pig ileum. The ED50 and pD2 values for the HWE was lower than those of ACh and histamine. Cyproheptadine and promethazine (10 ng/mL) significantly antagonized the effects of histamine, 5-hydroxytryptamine (5-HT) and HWE. Atropine blocked the effect of ACh and partially blocked the HWE. The calcium channel blockers nifedipine and verapamil both blocked the effects of all the agonists including HWE. These results suggest that the HWE contains potent histamine receptor stimulants or principles as it was blocked by low doses of H1 receptor blockers. It appears that stimulation of the receptors leads to influx of calcium since the effect was also blocked by nifedipine and verapamil. It is likely that it also stimulates muscarinic receptors. © 1997 John Wiley & Sons, Ltd. |
