RESUMO
The influence of cardamom seed volatile oil [V.O.] was investigated in the cardiovascular system of the rat, the nictitating membrane of the cat, the isolated rabbit jejunum, the isolated guinea-pig ileum and the frog sciatic nerve preparation. Intravenous administration of the oil in doses of[5-20 [micro]l Kg[-1]] induced dose-dependent decreases in the arterial blood pressure and the heart rate. It did not depress the isolated perfused rat heart. The depressant effects were significantly antagonized by treatment of the animals with cyproheptadine [1 mg Kg[-1] for 5 min] but not with mepyramine, ranitidine, hexamethonium, indomethacin or cutting of the vagus nerves. Atropine only antagonized the induced bradycardia. V.O. did not affect the electrically induced contraction of the cat nictitating membrane. Addition of the oil to the spontaneously contracting rabbit jejunum in small doses [0.08 [micro]l ml[-1]contracted the tissue but large doses relaxed it. Large doses of the V.O. also antagonized the stimulant effects of ACh, nicotine and BaCI[2] on the rabbit jejunum. Addition of the volatile oil in doses of[0.01-0.04 micro l/ml] to the isolated guinea-pig ileum contracted the tissue. The stimulant effect was antagonized by treatment of the tissue with atropine or cyproheptadine Furthermore, exposure of the frog's sciatic nerve to the oil in concentrations of [0.2-0.4 [micro]l/ml] suppressed the frog-limb withdrawal reflex suggesting a local anaesthetic effect. The stimulant component seemed to be due to activation of serotoninergic and cholinergic mechanisms and the relaxant effect seemed to be due to a local anaesthetic action. It was concluded that V.O.-induced actions were due to more than one of its constituents that possessed local anaesthetic coupled with serotoninergic and/or muscarinic agonistic activities