Extracts Of The Tuber Of Alisma Orientalis Relax Contraction Of Airway Smooth Muscle

Airway smooth muscle?ASM?is a key factor that controls airway diameter.Abnormal contraction of ASM is the main cause of airway obstruction and dyspnea.Thus,this paper aimed to find a drug that can relax ASM from traditional Chinese herbal,and clarify the mechanism,providing a foundation for developing new drugs for asthma.Our results showed that 1 mg/mL of ethanol extract of the tuber of Alisma orientalis?EEA?completely relaxed ACh and 80 mM K⁺-induced contraction of mouse tracheal rings and bronchial smooth muscles.Nifedipine?L-type voltage-dependent calcium channel selective inhibitor?,YM-58483?store-operated calcium channel specific inhibitor?and Y27632?ROCK inhibitor?partially relaxed ACh-induced contraction of tracheal rings,while the remained was inhibited by EEA.Nifedipine and YM-58483 respectively blocked the currents mediated by L-type voltage-dependent calcium channels?LVDCCs?and store-operated calcium channels?SOCCs?,which were also inhibited by EEA.ACh induced increases of intracellular calcium,which were reduced by EEA.At 0 mM Ca²⁺conditions,ASM showed only a small contraction after ACh stimulation,following the addition of 2 mM Ca²⁺,a large contraction occurred and inhibited by EEA.In addition,EEA reduced the phosphorylation level of myosin phosphatase target subunit 1?MYPT1?that is a linker of the calcium-sensitive pathway,and decreased mouse respiratory resistance.Conclusion:EEA relaxes contraction of ASM by inhibiting LVDCCs,SOCCs and Ca²⁺sensitization.Therefore,EEA could be developed as a new drug for the treatment of asthma.