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 ß 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 CaCl2 (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.