Abstract: To explore the effects of Urtica cannabina (UC) on uterus motility and its possible mechanism,alcohol extracts of UC at increasing doses (0.5%,1.0%,2.0%,4.0%,8.0% and 16.0%) were added to non-pregnant rat uterus in vitro.Changes of contraction frequency,contraction tension and contraction amplitude were recorded by biological signal processing system.Moreover,the combined effects of specific M-receptor antagonist atropine sulfate (A) at the dose of 2.5 μg/mL and UC at a dose of 2.0% on the motility of rat uterus were tested.There were three treatments,UC alone,UC+A and A+UC.The results showed that the contraction frequency was significantly increased when the concentration of UC arrived 4.0% compared with that before treatment (P <0.05);When the concentrations arrived 4.0% and 8.0%,contraction amplitudes of the uterus were extremely significantly decreased compared with that before treatment (P< 0.01);However,the contraction tension was not affected by the increasing concentrations of UC (P >0.05).When 2.0% UC alone treatment,uterus contraction tension increased rapidly and was close to rigidity,and then gradually decreased.Contraction frequencies after UC+A or A+UC treatments were extremely significantly faster than that before treatment (P <0.01),but the difference between the two combined treatments was not significant (P >0.05).Contraction tension of uterus after UC+A and A+UC treatments were extremely significantly reduced compared with that after UC alone treatment (P <0.01).The results indicated that UC could stimulate the contraction of rat uterus partly medicated by M-receptor,whereas there maybe were some other mechanisms involved in the effect.

Key words: Urtica cannabina; uterus; in vitro; smooth muscle