Antispasmodic effect of Mentha piperita essential oil on tracheal smooth muscle of rats

Aim of the study: Mentha piperita is a plant popularly known in Brazil as hortela-pimenta whose essential oil is used in folk medicine for its anti-inflammatory, antispasmodic, expectorant actions and anti-congestive. Here, it was investigated the effect of Mentha piperita essential oil (peppermint oil) in rat tracheal rings along with its mechanism of action. Materials and methods: Tracheal tissue from Male Wistar rats (250-300g) were used. Peppermint oil was added in cumulative concentrations [1-300 mu g/ml] to the tissue basal tonus or pre-contracted by carbachol [10 mu M] at 10 min intervals, incubated or not with indomethacin [10 mu M], t-N-metyl-nitro-arginine [100 mu M], hexamethonium 1500 mu M], or tetraethylammonium [5mM]. Results: Peppermint oil [100 and 300 mu g/ml] inhibited the contractions induced by carbachol, which was reversed by indomethacin, t-N-metyl-nitro-arginine and hexamethonium, but not by tetraethylammonium. These data suggest the participation of prostaglandin E-2, nitric oxide and autonomic ganglions in the peppermint oil relaxant effect and may be correlated with its popular use in respiratory diseases. Conclusions: Peppermint oil exhibited antispasmodic activity on rat trachea involving prostaglandins and nitric oxide synthase. (C) 2010 Elsevier Ireland Ltd. All rights reserved.