Background and Aims: The antioxidant and anti-inflammatory effects of carvacrol were reported. The aim of the current study was an investigation the relaxant effects of carvacrol on acetylcholine-induced contraction in isolated rat's ileum.

Materials and Methods: In this study, the tissues separated from ileum were fixed on the organ bath containing Tyrode's solution. The amplitude of contractions has been recorded using isotonic transducer. Before and after subjecting the tissues with saline and different concentrations of carvacrol,the procedure was elicited by cumulative logarithmic concentrations of acetylcholine (Ach).

Results: Our results indicated that carvacrol at 10^-2, 10^-3 and 10^-4, but not 10^-5 M decreased acetylcholine (10^-4 M)-induced contraction (10^-2 M at p<0.001; 10^-3 and 10^-4 at p<0.05 vs. Ach+saline). The antispasmodic effect of carvacrol was examined and showed that in concentrations of 10^-5, 10^-4 and 10^-3 M, but not 10^-6 M, the contractive effect of acetylcholine10^-3 M was prevented significantly. The concentrations of 1, 2 and 4 µM of verapamil were also tested and indicated that 4 µM of verapamil reduced contraction by 22.1±.5% (p<0.01 vs. saline). In samples treated with combined carvacrol (10^-5 M) and verapamil (4 µM) contraction percentage was decreased by 35±14%, which was significantly different compared to the Ach+saline group as well as the single treated groups (p<0.01 and p<0.05, respectively).

Conclusions: According to our findings, due to the effect of carvacrol and verapamil, the relaxant mechanism of carvacrol may be mediated by Ca⁺² release from the sarcoplasmic reticulum and the response of the contractile system.