Relaxant and antispasmodic actions of methyleugenol on guinea-pig isolatedileum

The effects of methyleugenol (ME) on guinea-pig isolated ileum were studied . ME reversibly relaxed basal tonus (EC50 of 52.2 +/- 18.3 mu M), an action unaltered by 0.5 mu M tetrodotoxin or 0.5 mM hexamethonium, and relaxed th e ileum precontracted with 60 mM KCI. ME slightly hyperpolarised the ileum from -57.3 to -62.8 mV but had no effect in depolarised tissues. ME inhibit ed contractions induced by ACh, histamine and KCl with IC50 values of appro ximately 82, 124, and 65 mu M, respectively. Our results suggest that ME in duces relaxation of guinea-pig ileum by a direct action on smooth muscle vi a a mechanism largely independent of alterations of membrane potential (E-m ).