Relaxant effect of diallyl sulfide on nonpregnant rat uterus: Involvement of voltage‐dependent calcium channels

Aim We aimed to determine the effect and mechanism of action of diallyl sulfide (DAS), an active component of sulfur‐containing foods such as garlic on rat uterine activity. Methods Isometric tension changes in longitudinal uterine strips obtained from 20 female Sprague–Dawley rats (250–300 g) in estrus stage of estrous cycle were studied in isolated organ baths containing Krebs–Henseleit solution. Results Diallyl sulfide (10 −8 –10 −6  M) caused a concentration‐dependent relaxation on KCl (60 mM)‐induced contractions and inhibited spontaneous peristaltic activity of uterine strips ( P  < 0.05). None of the following antagonists significantly changed the inhibitory effect of DAS on both KCl‐precontracted uterine strips and spontaneous peristaltic activity of the uterus ( P  > 0.05): nitric oxide synthase inhibitor L‐NAME (10 −4  M), hydrogen sulfide‐producing enzymes cystation β synthase and cystation γ‐lyase inhibitors, aminooxyacetic acid (10 −4  M) and propargylglycine (10 −3  M) and nonselective cyclooxygenase inhibitor indomethacin (10 −4  M). However, in calcium‐free Krebs solution containing high KCl (30 mM), DAS significantly inhibited CaCl 2 (10 −5 –10 −2  M)‐induced uterine contractions in a concentration‐dependent manner ( P  < 0.05). Conclusion Diallyl sulfide has a relaxing effect on KCl‐contracted rat uterus strips and an inhibitory effect on spontaneous uterine activity, possibly by decreasing the calcium influx into the cytoplasm of uterine smooth muscle cells.