The relaxant effect induced by Allium sativum L. bulb aqueous extract on rat isolated trachea

Background: Garlic plays an important role in complementary and alternative medicine. Most people believe in and use herbal products even when they have not been as thoroughly researched as garlic. Garlic is also known for its beneficial effects on the cardiovascular system. Materials and Methods: The relaxant effect of Allium sativum L. bulb aqueous extract (ASBAE) containing 0.06%-0.10% of allicin was studied on isolated smooth muscle of trachea of rats precontracted using acetylcholine (10⁻⁵ M). Results: It was found that ASBAE induced a dose-dependent relaxation with recorded EC ₅₀ values of 71.87 ± 5.90 μg/mL (n = 7). Pretreatments with mepyramine (10⁻⁷ M), methysergide (10⁻⁷ M), caffeine (10⁻⁶ M), theophylline (10⁻⁶ M), nifedipine (10⁻⁶ M), and dipyridamole (10⁻⁶ M) did not alter ASBAE concentration-response curves. In turn, concentration-response curves to ASBAE were significantly shifted toward right in the presence of aspirin (3.10⁻³ M), indomethacin (10⁻⁶ M), prazosin (10⁻⁶ M), and propranolol (10⁻⁷ M). Conclusion: It is suggested that the recorded relaxation results are due to the release of prostaglandins E ₁ and E ₂ consecutively to a- and b-adrenoreceptor stimulation.