title: Bronchorelaxant property of 'African potato' (Hypoxis hemerocallidea corm) aqueous extract in vitro.
abstract: This study was undertaken to investigate the bronchorelaxant effect of Hypoxis hemerocallidea corm ('African potato') aqueous extract (APE) on spasmogen-provoked contractions of guinea-pig isolated tracheal smooth muscle preparations. APE (25-400 mg/ml) relaxed spasmogen (histamine-, carbachol- and potassium-)-induced contractions of the isolated tracheal muscle preparations in a concentration-dependent manner. The relaxant effects of APE on spasmogen-evoked contractions of the tracheal muscle preparations were not altered by bath-applied propranolol (0.1-5.0 microg/ml), which markedly inhibited or completely abolished the relaxant effects of isoprenaline (0.1-5.0 microg/ml). Although the precise mechanism of the bronchorelaxant effect of APE could not be established in the present study, it is unlikely that the herb's aqueous extract stimulates the beta(2)-adrenoceptors present on the bronchial smooth muscles to produce its bronchodilatation. The finding that APE significantly relaxed (P<0.05) histamine-, carbachol- and high potassium ion concentration (K(+), 80 mM)-induced contractions of guinea-pig isolated bronchial muscle preparations appears to suggest that the bronchospasmolytic effect of the plant's extract is probably not mediated through a specific receptor, but rather, probably mediated via a non-specific bronchospasmolytic mechanism.
authors.affiliation: Department of Pharmacology, School of Pharmacy & Pharmacology, Faculty of Health Sciences, University of KwaZulu-Natal, Durban 4000, South Africa. ojewolej@ukzn.ac.za
authors.forename: John A O
authors.initials: JA
authors.lastname: Ojewole
authors.forename: Gbola
authors.initials: G
authors.lastname: Olayiwola
authors.forename: Agatha
authors.initials: A
authors.lastname: Nyinawumuntu
mesh_terms: D000818:Animals; D001980:Bronchi / Q000187:drug effects*; D002217:Carbachol / Q000494:pharmacology; D005260:Female; D006168:Guinea Pigs; D006632:Histamine / Q000494:pharmacology; D027802:Hypoxis / Q000737:chemistry*; D066298:In Vitro Techniques; D020128:Inhibitory Concentration 50; D008297:Male; D016488:Medicine, African Traditional; D009126:Muscle Relaxation / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology; D010936:Plant Extracts / Q000494:pharmacology*; D014132:Trachea / Q000187:drug effects / Q000502:physiology
chemical_list: D010936:Plant Extracts; D006632:Histamine; D002217:Carbachol