Objective:To determine the appropriate time of early administration of dopamine（DA） before nitroglycerin（GTN） for establishing rat model with vasomotor abnormalities.Methods: Rats were divided into 5 groups: normal group

DA Group and other 3 groups in accordance with DA at different time points（10

30

45 min） plus GTN.Common carotid artery（CCA） blood flow velocity was dynamically measured with pulsed Doppler flow probe to evaluate the influence of DA

GTN on blood flow velocity rate（BFVR）.Results:The blood flow velocity rate induced by DA of All medication administration was different from the normal group within 10 minutes（P<0.05）.However

the differences were not statistically significant after 11 min（P>0.05）.The BFVR of 10min interval group had differences with the DA group at 45min

50min

55min

60min

65min and 70min（P<0.05 or P<0.01）.CCA BFVR of 45 min interval group was statistically significant different from the DA group at 80

85

90

95 min and 100 min（P<0.05）.No statistically significant differences existed between CCA BFVR of 30min interval group and DA group（P>0.05）.Conclusion: Subcutaneous injection of DA

45min after injection of GTN can induce vasomotor abnormalities in rat with phase characters.The model may be useful for vasoactive screening of anti-migraine drugs.