Antidiarrheal effect of ethanol extract from Lophatheri Herba and its effect on isolated jejunal smooth muscle in rabbits

Lophatheri Herba is a traditional Chinese medicine, which is commonly used in the treatment of fever, stomatitis, urodynia. The aim of the study is to evaluate the antidiarrheal activity of the ethanol extract of Lophatheri Herba (Gramineae, ELH) and observe its effect on isolated jejunum smooth muscle in rabbits, so that we can provide a possible pharmacological basis for its clinical use. Methods: In vivo, the antidiarrheal activity of ELH (250, 500 and 1000 mg/kg; orally) in castor oil-induced Kun Ming mice was evaluated. In vitro, the effect of ELH (0.01-10 mg/mL) on the spontaneous and ACh (10μM)/K⁺ (60mM)-induced contraction of isolated rabbit jejunum smooth muscle was studied. The possible mechanism of spasmolytic effect of ELH (1, 3mg/mL) was explored by pretreatment of intestinal tract with CaCl₂. Results: ELH (500 and 1000mg/kg) exhibited antidiarrheal effect and it (0.01-10 mg/mL) inhibited the spontaneous and ACh/K+-induced contraction with an EC₅₀ value of 1.27 (0.89-1.34), 0.76 (0.54-1.02) and 0.34 (0.27-0.53), it also shifted the concentration-response curves of CaCl₂ to right with decreased in max, similar to verapamil. ELH has significant antidiarrheal and spasmolytic effect, this provides the pharmacological basis for use in gastrointestinal disorders.