title: Effects of alkaloids of Himatanthus lancifolius (Muell. Arg.) Woodson, Apocynaceae, on smooth muscle responsiveness.
abstract: Himatanthus lancifolius, popularly known as "agoniada" in Brazil, is largely used in folk medicine against asthma, dysmenorrhea and as an emenagogue and abortive. This study reveals the effects of an alkaloid rich fraction (AlkF) obtained from the bark of Himatanthus lancifolius in vascular and non-vascular smooth muscle responsiveness. Incubation of AlkF (3-30 microg/ml) during 15 min generates a concentration-related and fully reversible reduction in maximal contractile responses evoked by acetylcholine and phenylephrine in rat jejune and aorta preparations, respectively. Exposition of endothelium-denuded pre-contracted rat aorta rings to AlkF results in a complete relaxation, with EC(50) of 22.2 (16.2-28.2 microg/ml). AlkF is also able to induce a concentration-related rightward shift of cumulative concentration curves for calcium in uterus and aorta rings maintained in depolarizing nutritive solution. Moreover, addition of AlkF in calcium-free solution also reduces, in a concentration-dependent manner, the ability of caffeine and phenylephrine to contract aorta rings. This study reveals that the bark of Himatanthus lancifolius possesses one or more indole alkaloids able to alter non-vascular and vascular smooth muscle responsiveness, an event that may involve the blocking of calcium entry or changes on intracellular calcium utilization or mobilization.
authors.affiliation: Department of Pharmacology, Biological Sciences Sector, Universidade Federal of Paraná, Curitiba, Brazil.
authors.forename: Yanna D
authors.initials: YD
authors.lastname: Rattmann
authors.forename: Márcia R
authors.initials: MR
authors.lastname: Terluk
authors.forename: Wesley M
authors.initials: WM
authors.lastname: Souza
authors.forename: Cid A M
authors.initials: CA
authors.lastname: Santos
authors.forename: Maique W
authors.initials: MW
authors.lastname: Biavatti
authors.forename: Luce B
authors.initials: LB
authors.lastname: Torres
authors.forename: Sonia
authors.initials: S
authors.lastname: Mesia-Vela
authors.forename: Lia
authors.initials: L
authors.lastname: Rieck
authors.forename: José E
authors.initials: JE
authors.lastname: da Silva-Santos
authors.forename: Maria C de A
authors.initials: MC
authors.lastname: Marques
mesh_terms: D000109:Acetylcholine / Q000037:antagonists & inhibitors / Q000494:pharmacology; D000470:Alkaloids / Q000737:chemistry / Q000494:pharmacology*; D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects; D029062:Apocynaceae / Q000737:chemistry*; D002118:Calcium / Q000502:physiology; D002122:Calcium Chloride / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D005260:Female; D007082:Ileum / Q000187:drug effects; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009129:Muscle Tonus / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects; D010656:Phenylephrine / Q000494:pharmacology; D024301:Plant Bark / Q000737:chemistry; D051381:Rats; D017208:Rats, Wistar; D014590:Uterine Contraction / Q000187:drug effects; D014649:Vas Deferens / Q000187:drug effects; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014665:Vasodilator Agents / Q000037:antagonists & inhibitors / Q000494:pharmacology
chemical_list: D000470:Alkaloids; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D010656:Phenylephrine; D002122:Calcium Chloride; D000109:Acetylcholine; D002118:Calcium