Myorelaxant effects of the essential oil of Croton nepetaefolius on the contractile activity of the guinea-pig tracheal smooth muscle.
The effects of the essential oil of Croton nepetaefolius (EOCN) on isolated guinea-pig trachea were investigated. EOCN decreased the preparation's basal tone (EC (50) = 4.3 microg/mL) with a maximal effect similar to that of aminophylline. EOCN fully relaxed preparations pre-contracted with 60 mM K+ (IC (50) = 113.0 microg/mL). EOCN did not alter the E (m) of smooth muscle cells in 5 and 80 mM K+. EOCN, at 300 and 600 microg/mL, reduced the contraction induced by ovalbumin (10 microg/mL) from 227.2 to 82.5 and 35.5 % of the 60 mM K+-induced contraction, respectively. EOCN blocked the submaximal contractions induced by histamine, carbachol and 60 mM K+ with a similar potency (IC (50) values = 123.9, 102.5 and 128.8 microg/mL, respectively). In conclusion, EOCN exerts respiratory smooth muscle antispasmodic activity by a mechanism that is probably myogenic and not specific for neurotransmitters and autacoids.
Departamento de Fisiologia e Farmacologia, Faculdade de Medicina, Universidade Federal do Ceará, Av. Paranjana 1700, 60740-000 Fortaleza, Ceará-CE, Brazil.
Pedro Jorge Caldas
PJ
Magalhães
Saad
S
Lahlou
Márcia Andréa
MA
Vasconcelos dos Santos
Tatiana Leite
TL
Pradines
José Henrique
JH
Leal-Cardoso
D000818:Animals; D029802:Croton; D006168:Guinea Pigs; D020128:Inhibitory Concentration 50; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects; D010047:Ovalbumin; D010276:Parasympatholytics / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D008517:Phytotherapy; D010938:Plant Oils / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D014132:Trachea / Q000187:drug effects
D010276:Parasympatholytics; D010938:Plant Oils; D010047:Ovalbumin