Cardiovascular effects induced by Cymbopogon winterianus essential oil in rats: involvement of calcium channels and vagal pathway.
OBJECTIVE
This study has investigated the cardiovascular effects of the Cymbopogon winterianus essential oil (EOCW) in rats. C. winterianus is a plant used in folk medicine for the treatment of hypertension.


METHODS
For the measurement of haemodynamic and ECG parameters, male Wistar rats under anaesthesia were cannulated in the abdominal aorta and lower vena cava and electrodes were subcutaneously implanted in their paws. For an in-vitro approach, the rats were killed and the superior mesenteric artery was removed and cut into rings (1-2 mm). These rings were then mounted in organ baths containing Tyrode's solution at 37 degrees C and gassed with carbogen.


RESULTS
In rats, EOCW (1-20 mg/kg, i.v.) induced dose-dependent hypotension and tachycardia. These effects were not affected by L-NAME or indometacin, but were partially reduced after atropine administration. EOCW (20 mg/kg only) also induced bradycardia-associated sinoatrial blockade, junctional rhythm, and first-degree atrioventricular block, which was abolished after atropine administration or vagotomy. In arterial rings, EOCW (0.1-3000 microg/ml) induced relaxation of phenylephrine tonus that was not affected by removal of the endothelium. These relaxations were similar to those observed in rings without endothelium precontracted with KCl 80 mm. EOCW was able to antagonize the CaCl(2) (30-300 mum) induced contractions in depolarizing solution (KCl 60 mm).


CONCLUSIONS
These results demonstrated that EOCW induced hypotension and vasorelaxation. These effects appeared to be mainly mediated by Ca(+2)-channel blocking. Furthermore, the higher dose of EOCW induced transient bradycardia and arrhythmias due to a cardiac muscarinic activation secondary to a vagal discharge.
de Menezes
Igor Alexandre Côrtes
IA
Department of Physiology, Federal University of Sergipe, São Cristóvão, SE, Brazil.
Moreira
Italo José Alves
IJ
de Paula
José Welton Azevedo
JW
Blank
Arie Fitzgerald
AF
Antoniolli
Angelo Roberto
AR
Quintans-Júnior
Lucindo José
LJ
Santos
Márcio Roberto Viana
MR
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D015220:Calcium Channels / Q000378:metabolism*; D031743:Cymbopogon / Q000737:chemistry*; D004305:Dose-Response Relationship, Drug; D004569:Electroencephalography; D006321:Heart / Q000187:drug effects* / Q000294:innervation / Q000502:physiology; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects*; D066298:In Vitro Techniques; D007551:Isotonic Contraction / Q000187:drug effects; D008297:Male; D017538:Mesenteric Artery, Superior / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects; D009822:Oils, Volatile / Q000302:isolation & purification / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D014628:Vagotomy; D014630:Vagus Nerve / Q000187:drug effects* / Q000502:physiology; D014664:Vasodilation / Q000187:drug effects
D015220:Calcium Channels; D009822:Oils, Volatile