The pharmacological action of Rhoicissus tridentata on isolated rat uterus and ileum

Decoctions and infusions of Rhoicissus tridentata subsp cuneifolia (Vitaceae) roots and lignotubers are widely used in South African traditional herbal remedies during pregnancy. The pharmacological action of an aqueous extract of R. tridentata subsp cuneifolia roots was investigated using isolated rat uterus and ileum. The extract directly stimulated concentration dependent contractions of the uterus and ileum. Pretreatment with the muscarinic antagonist atropine (40 nM) and the cyclooxygenase inhibitor indomethacin (5 microM) both blocked the contractile response to the Rhoicissus extract suggesting that muscarinic receptors and cyclooxygenase metabolites could be involved in the contractile response to the extract. The serotonergic antagonist methysergide (1 microM) and the alpha-adrenoceptor antagonist prazosin (2 microM) had no effect on the direct action of the extract. This infers that the contractile response to the plant extract is independent of serotonin receptors and alpha-adrenoceptors.