Abstract: AIM: To investigate the effects of three extracts of Fufang Dihuang decoction on the relaxation of mesentery artery in streptozotocin(STZ)-induced diabetic rats.METHODS: Diabetic rat model was induced by i. p injection STZ at a dosage of 60 mg·kg^-1.30 d later, 95%ethanol, 70%ethanol or water extract of Radix Re-hmanniae was p.o administrated for 30 d at the dosage of 107.8, 154.7 and 56.8 mg·kg^-1, respectively.On the 60th day, the responses of mesentery artery were deter-mined in the absence or presence of L-argine (L-Arg), N-Nitro-L-argine (NLA) and Indomethacin (Ind).RESULTS: The relaxation of mesentery artery of diabetic rat was diminished compared with the normal control.The basal release of NO and the L-argine-induced release of NO decreased 64.6%, 77.6% respectively in diabetic group compared with the normal control, with the de-creased proportion of NO in the endothelium dependent relaxation.95% and 70 %ethanol extract of Fufang Di-huang decoction ameliorated the impaired release of NO in rat' s mesentery artery.CONCLUSION: Abnormal re-laxation of mesentery artery in diabetic rat may be due to the decreased releasing of NO.The extracts of Fufang Di-huang decoction can protect the endothelium cells and im-prove the relaxation of mesentery artery, among them 70%ethanol extract exert the best potency, followed by 95%ethanol extract.And the water extract has a poor ef-fect.

Key words: Fufang Dihuang decoction, diabetic mellitus, mesentery artery, nitric oxide, streptozotocin