[ ABSTRACT] AIM: To investigate the underlying mechanisms responsible for endothelial dysfunction of type 1 diabetes mellitus (DM) rats fed with high-salt diet.METHODS:Type 1 DM was induced by intraperitoneal injection of streptozotocin (70 mg/kg).Normal and diabetic rats were fed high-salt food (HS, 8% NaCl) and standard food for 6 weeks, respectively.Isometric tension of the mesenteric arteries were measured .The expression of Akt , endothelial nitric oxide synthase (eNOS) and caveolin-1 (Cav-1) was examined by Western blot .RESULTS:The rats in DM+HS group exhibited more pronounced impairment of vasorelaxation to acetylcholine and insulin compared with either DM group or HS group (P<0.01).Akt and eNOS phosphorylation levels, and nitric oxide (NO) concentration in DM +HS group were significantly lower than those in DM group (P<0.01).The level of Cav-1 in DM+HS group was significantly higher than that in DM group and HS group .CONCLUSION:Impaired endothelial Akt activation , increased Cav-1 expression and re-sultant decreased eNOS activation contribute to aggravate high-salt diet-induced endothelial dysfunction and hypertension in DM rats.