Abstract
BackgroundAlkaloids extracted from lotus leaves (AELL) can relax vascular smooth muscle. However, whether AELL has a similar relaxant role on airway smooth muscle (ASM) remains unknown. This study aimed to explore the relaxant property of AELL on ASM and the underlying mechanism.MethodsAlkaloids were extracted from dried lotus leaves using the high temperature rotary evaporation extraction method. The effects of AELL on mouse ASM tension were studied using force measuring and patch-clamp techniques.ResultsIt was found that AELL inhibited the high K+ or acetylcholine chloride (ACh)-induced precontraction of mouse tracheal rings by 64.8 ± 2.9%, or 48.8 ± 4.7%, respectively. The inhibition was statistically significant and performed in a dose-dependent manner. Furthermore, AELL-induced smooth muscle relaxation was partially mediated by blocking voltage-dependent Ca2+ channels (VDCC) and non-selective cation channels (NSCC).ConclusionAELL, which plays a relaxant role in ASM, might be a new complementary treatment to treat abnormal contractions of the trachea and asthma.
Highlights
Alkaloids extracted from lotus leaves (AELL) can relax vascular smooth muscle
The results show that high K+ or acetylcholine chloride (ACh)-precontracted mouse airway smooth muscle (ASM) could be relaxed by AELL in a concentrationdependent manner
AELL Dose-dependently Inhibit High K+-induced Precontraction A high K+ concentration causes the contraction of smooth muscle through the membrane depolarizationVDCC open-calcium influx pathway [35, 36]
Summary
Whether AELL has a similar relaxant role on airway smooth muscle (ASM) remains unknown. This study aimed to explore the relaxant property of AELL on ASM and the underlying mechanism. Asthma and chronic obstructive pulmonary disease (COPD), two typical airway problems, have been linked to decreased quality of life, increased medical costs and even mortality and may be an underlying factor for lung cancer [2]. Airway smooth muscle (ASM), a particular cell type in the airway system, plays a vital role in airway obstruction during asthma and COPD. The pharmacological treatment of asthma and COPD mainly relies upon β2 agonists and muscarinic antagonists, which can affect β2-adrenergic and muscarinic receptors, respectively. Novel drugs are urgently needed for these airway diseases
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