Relaxant and antispasmodic actions of methyleugenol on guinea-pig isolated ileum.

The effects of methyleugenol (ME) on guinea-pig isolated ileum were studied. ME reversibly relaxed basal tonus (EC50 of 52.2 +/- 18.3 microM), an action unaltered by 0.5 microM tetrodotoxin or 0.5 mM hexamethonium, and relaxed the ileum pre-contracted with 60 mM KCl. ME slightly hyperpolarized the ileum from -57.3 to -62.8 mV but had no effect in depolarised tissues. ME inhibited contractions induced by ACh, histamine and KCl with IC50 values of approximately 82, 124, and 65 microM, respectively. Our results suggest that ME induces relaxation of guinea-pig ileum by a direct action on smooth muscle via a mechanism largely independent of alterations of membrane potential (Em).