Effect of the hydroalcoholic extract of rauwolfia ligustrina on smooth and cardiac muscles in-vitro.
The actions of the hydroalcoholic extract (HE) of Rauwolfia ligustrina (the whole plant) on agonist-induced contractions were analysed in the rat uterus and guinea-pig ileum and trachea, and also in rat atrium contracting spontaneously in-vitro. The HE (100-400 micrograms mL-1) caused concentration-dependent rightward shifts of the concentration-response curves and reduced the maximal contraction induced by oxytocin, bradykinin, angiotensin II, prostaglandin F2 alpha and acetylcholine in the rat uterus. The calculated mean IC50 values were: 300, 147, 158, 197 and 105 micrograms mL-1, respectively. In the guinea-pig ileum the HE also caused graded displacement to the right of the concentration-response curves for bradykinin, histamine and carbachol, associated with pronounced inhibition of the agonist-induced maximal contractions. The calculated mean IC50 values were 165, 134 and 241 micrograms mL-1, respectively. The HE (100-3000 micrograms mL-1) caused graded relaxation (IC50 of 271 micrograms mL-1) of strips of guinea-pig trachea precontracted with carbachol (0.2 microM). This effect was not influenced by propranolol (1 microM), 3-isobutyl-1-methylxanthine (1 microM) or methylene blue (10 microM), but was significantly potentiated (1.5-to 3-fold) by indomethacin (3 microM) and forskolin (1 nM). In addition, NG-monomethyl-L-arginine (L-NMMA, 100 nM) significantly reduced the HE-induced maximal relaxation, while indomethacin (3 microM) potentiated the HE response. Finally, the HE caused a concentration-dependent and long-lasting inotropic effect in the rat right atrium, contracting spontaneously with a mean EC50 value of 409 micrograms mL-1. It is suggested that the effects of the HE of R. ligustrina on smooth and cardiac muscles "in-vitro' may result from its ability to interact, at least partially, with the cAMP pathway.
Medeiros
C L
CL
Departamento de Ciências Básicas da Saúde e Laboratório de Tecnologia Farmacêutica, Universidade Federal da Paraíba, João Pessoa, Brazil.
Calixto
J B
JB
D000818:Animals; D004305:Dose-Response Relationship, Drug; D005260:Female; D006168:Guinea Pigs; D006321:Heart / Q000187:drug effects*; D007082:Ileum / Q000187:drug effects; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects*; D009200:Myocardial Contraction / Q000187:drug effects; D010946:Plants, Medicinal; D051381:Rats; D017208:Rats, Wistar; D046948:Secologanin Tryptamine Alkaloids / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D013268:Stimulation, Chemical; D013565:Sympatholytics / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D014132:Trachea / Q000187:drug effects; D014599:Uterus / Q000187:drug effects; D019323:omega-N-Methylarginine / Q000494:pharmacology
D046948:Secologanin Tryptamine Alkaloids; D013565:Sympatholytics; D019323:omega-N-Methylarginine