Activity of Cecropia lyratiloba extract on contractility of cardiac and smooth muscles in Wistar rats.
1. Brazilian forests show high diversity of medicinal plants and several are used in folk medicine for the treatment of hypertension and asthma. The aim of the present study was to investigate the effects of a methanol extract (ME) of Cecropia lyratiloba and its flavonoid fraction (FF) on the contractility of cardiac, vascular and tracheal smooth muscles. 2. Twitches of rat papillary muscles were obtained with electrical stimulation and were recorded before and after exposure to increasing concentrations of ME and FF. 3. Cardiac depression was induced by FF. At 500 microg/mL FF, the amplitude of twitches was reduced to 56.7 +/- 5.1% of control values (P < 0.05). 4. The contractile response to a single concentration of adrenaline (10 micromol/L) was measured before and after exposure to ME and FF in rat aorta rings with intact endothelium. Both ME and FF inhibited adrenaline-induced contractions of the aorta in a concentration-dependent manner. Adrenaline-induced contractions were reduced to 46.4 +/- 9.9 and 34.2 +/- 6.9% (P < 0.05) of control in the presence of 500 microg/mL ME and FF, respectively. 5. The flavonoids isolated from FF, namely isoorientin and a mixture of orientin and isovitexin, were also tested in the aorta. These flavonoid do not seem to be responsible for the vasorelaxant effects of ME and FF. 6. No changes were observed in acetylcholine-precontracted trachea when exposed to ME or FF. 7. Endothelium-dependent vasodilation induced by FF is likely to be mediated by the release of nitric oxide because vascular relaxation was abolished in the presence of N(omega)-nitro-L-arginine methyl ester, an inhibitor of nitric oxide synthase. 8. In conclusion, vascular relaxation induced by ME and FF could explain the traditional use of the extract of C. lyratiloba for treatment of arterial hypertension.
Ramos Almeida
Roberta
R
Departamento de Farmacologia Básica e Clinica, Instituto de Ciências Biomédicas, Universidade Federal do rio de Janeiro, Rio de Janeiro, Brazil.
Montani Raimundo
Juliana
J
Rodrigues Oliveira
Rodrigo
R
Coelho Kaplan
Maria Auxiliadora
MA
Gattass
Cerli Rocah
CR
Sudo
Roberto Takashi
RT
Zapata-Sudo
Gisele
G
D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects / Q000502:physiology; D035702:Cecropia Plant / Q000737:chemistry*; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004837:Epinephrine / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D066298:In Vitro Techniques; D007537:Isometric Contraction / Q000187:drug effects; D008297:Male; D000432:Methanol / Q000737:chemistry; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology; D009200:Myocardial Contraction / Q000187:drug effects; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D010210:Papillary Muscles / Q000187:drug effects* / Q000502:physiology; D010936:Plant Extracts / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D018515:Plant Leaves / Q000737:chemistry; D051381:Rats; D017208:Rats, Wistar; D014132:Trachea / Q000187:drug effects / Q000502:physiology; D014661:Vasoconstriction / Q000187:drug effects; D014662:Vasoconstrictor Agents / Q000494:pharmacology
D004791:Enzyme Inhibitors; D005419:Flavonoids; D010936:Plant Extracts; D014662:Vasoconstrictor Agents; D019001:Nitric Oxide Synthase; D019331:NG-Nitroarginine Methyl Ester; D000432:Methanol; D004837:Epinephrine