Objective To explore the mechanism of Gonghuanzhixue Tablets for treating endometrorrhagia caused by copper intrauterine device (Cu-IUD). Methods In constrast withpregnendione and oxytocin, we investigated contraction activity of rats uterine smooth muscle by LMS two-path physiological recorder and JH-2 muscular tension transmitte. Results Gonghuanzhixue Tablets could enhance the activity of rats uterine smooth muscle, but have apparent counteraction to the fierce contraction activity of uterine smooth muscle caused by oxytocin. Conclusion Gonghuanzhixue Tablets can bidirectional regulate the ...