The Regulation Of Emodin And Quercetin On Smooth Muscle Contraction And The Function Of Smooth Muscle Myosin

Emodin is a major bioactive substance of Rheum Palmatum which has been widely used in China for hundreds of years in treating gastrointestinal disorders. Whether emodin can be used in clinics for the treatment of gastrointestinal disorder is one of the hot studies. Quercetin belongs to flavonoids which possess a wide spectrum of biological activities. Many flavonoids are found to dilate gastrointestinal smooth muscle, reduce peristalsis of small and large intestine in mice, and and prevent castor oil-induced diarrhea. No detailed studies dealing with the effects of quercetin on the smooth muscle were found. Considering the model of isolated intestinal assay is conventional for investigating the gastro-intestinal smooth muscle, we choose the model as one of the indexs to observe the direct regulation of emodin and quercetin on the smooth muscle.It is necessary to further investigate the the molecular mechanism of emodin and quercetin on smooth muscle for the previous study mainly on the organic level. It is generally accepted that smooth muscle contraction is activated primarily via Ca²⁺ -dependent phosphorylation of myosin (CDPM) by myosin light chain kinase (MLCK). Phosphrylated MLC20 interacts with actin producing force. Smooth muscle is relaxed after myosin dephophorelated by phopgatase. Since the changes in myosin phosphorylation and Mg²⁺-ATPase activity reflect the regulation myosin function, we choose them as important indexes to determine the effects of emodin and quercetin on myosin. What we have noticed and are interested in are as follows: (a) some medicinal herbs contain both emodin and...