目的 研究当归芍药散对大鼠在体子宫收缩、子宫内血管舒缩因子的影响，探讨其治疗原发性痛经的作用机制。方法 雌性未孕SD大鼠随机分为模型组，维拉帕米（100 μg/kg）阳性组，当归芍药散低、中、高剂量（生药4、8、16 g /kg）组，每天给药1次，连续给药7 d。第7天大鼠sc己烯雌酚4 mg/kg，次日在麻醉状态下观察给予缩宫素前后大鼠子宫收缩变化，同时测定药物对子宫组织匀浆中一氧化氮（NO）及内皮素（ET）量的影响。结果 当归芍药散显著提高正常大鼠子宫收缩的平均肌张力，而对缩宫素诱导的大鼠子宫收缩具有显著的抑制作用；对缩宫素处理前后的大鼠子宫收缩频率、幅度、平均肌张力及子宫活动力等的变化率有显著抑制作用；能够显著升高缩宫素处理后大鼠子宫NO水平，降低ET水平，使NO与ET比值显著上升。结论 当归芍药散可能通过抑制子宫收缩，调节血管舒缩物质，改善子宫供血，从而对原发性痛经产生治疗作用。

Objective To explore the effects of Danggui Shaoyao Powder (DSP) on in vivo uterine contractions and vasomotor factors of rats, and to investigate the mechanism of DSP for healing primary dysmenorrhea. Methods Female SD rats were randomly divided into model, Verapamil (100 μg/kg, positive control), low-, mid-, and high-dose DSP (4, 8, and 16 g/kg) groups, and the rats were administered once daily for 7 d. The rats were sc administered with diethylstilbestrol (4 mg/kg) on day 7, on the next day the in vivo uterine contraction of rats was observed before and after oxytocin treatment under anesthesia condition, and the levels of nitric oxide (NO) and endothelin (ET) in uterine homogenate were determined. Results DSP increased the average muscle tension of uterine contraction of normal rats obverously, but inhibited the oxytocin-induced uterine contraction significantly. The changes of the uterine contraction frequency, amplitude, average muscle tension, and uterine vigour of rats before and after oxytocin processing were significantly inhibited. DSP increased the NO level in the uterine of the experimental animals after oxytocin treatment and reduced the level of ET. The NO/ET ratio increased significantly. Conclusion DSP could inhibit the in vivo uterine contraction, regulate the vasomotor substances, and improve the uterine blood supplement, resulting in the beneficial effect on treating primary dysmenorrhea.