Saeideh Saadat - Neurogenic Inflammation Research Center and Department of Physiology, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
Javad Boskabady - Neurogenic Inflammation Research Center and Department of Physiology, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
Mohammad Hossein Boskabady - Neurogenic Inflammation Research Center and Department of Physiology, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran

Introduction: Bronchospasm is an important symptom of chronic obstructive pulmonary diseases (COPD), and any multi potential agent that relives contraction in thetrachea is effective in improving lung function in COPD and asthma.Baicalein, a compound extracted from a variety of herbs, showed various pharmacological actions such as vasodilatation effects. This study evaluated the relaxant effects of baicaleinon rat s isolated tracheal smooth musclevia in vitro preparation. Materials and Methods: Tracheal smooth muscle were contracted by 10 μM methacholine or 60 mMKCl and the effects of cumulative concentrations of baicaleinwith purity up to 98% (5,10, 20 and 40 mg/ml) and theophylline (0.2, 0.4, 0.6 and 0.8 mM) as a positive control, or 1 ml of normal saline as a negative control were evaluated. Contractionresponses were measured using an isometric transducer which was connected to a power lab system. Results: A significant and concentration-dependent relaxant effect was seen for baicaleinin tissues contracted by KCl or methacholine (P<0.01 to P<0.001). There was no significant difference in the relaxant effects of various concentrations of baicalein obtained in KCl-induced contraction with those in TSM contracted by methacholine. No significant difference was seen between the relaxant effects ofhigh concentrations of baicalein and theophylline. Conclusions: A relatively potent relaxant effect of baicalein comparable to the effect of theophylline was shown for baicalein.

Baicalein, Relaxation, Smooth Muscle, Trachea.