Abstract: Objective To determine the role of arginase inhibitor (nor-NOHA) on vascular remodeling in SHRs。Methods WKY rats were used as the control and SHR were randomly divided into untreated control(SHR) and treated group(SHR-T). SHR in the treated groups were injected intraperitoneally every day with nor-NOHA(40 mg/kg )for 10 weeks while the control groups were given to saline. Indirect tail-cuff systolic blood pressures and body weight were measured at given times. After the experiment ,The thoracic aorta、left ventricular（LV） and left kidney were taken . The contents of activated MMP-2 in these organs were measured by semi-quantitative gelatine-zymography，meanwhile Media thickness(MT), luminal diameter(LD), ratio of media to lumen (M/L) and collagen type I and Ⅲ, elastic fibers of thoracic aorta were measured by special Tricrome Masson, Picric-Sirius red and Orcein staining methods. Results (1) Blood pressure of treated group was significantly lower than untreated control groups;(2) Much more MMP-2 in LV exsited in SHR group than in SHR-T group .（3）MT and M/L of treated group were significantly smaller than untreated control groups in thoracic aorta； Much more collagen I and III existing in the vascular of untreated control group compare with treated group.；Conclusions nor-NOHA could relieve vascular remodeling probably by inhibiting the activity of MMP-2 and the synthesis of collagen I and III.

Key words: SHR, Vascular remodeling, Arginase inhibitor, MMP-2