AIM: To evaluate the antioxidant effect of N-acetylcysteine(NAC) on the stomach of rats with portal hypertension.METHODS: Twenty-four male Wistar rats weighing ± 250 g were divided into four experimental groups(n =6 each): Sham-operated(SO),SO + NAC,partial portal vein ligation(PPVL),and PPVL + NAC. Treatment with NAC in a dose of 10 mg/kg(i.p.) diluted in 0.6 m L of saline solution was administered daily for 7 d starting 8 d after the surgery. Animals from the PPVL and SO group received saline solution(0.6 m L) for the same period of time as the PPVL + NAC and SO + NAC group. On the 15 th day the animals were anesthetized and we evaluated portal pressure by cannulating mesenteric artery. After,we removed the stomach for further analysis. We performed immunohistochemical analysis for endothelial nitric oxide synthase(e NOS),vascular endothelial growth factor(VEGF),and nitrotirosine(NTT) proteins in stomach. We also evaluated e NOS and VEGF by Western blot analysis and assessed DNA damage in blood samples by the comet assay.RESULTS: The portal hypertension group exhibited increases in portal pressure when compared to SO group(29.8 ± 1.8 vs 12.0 ± 0.3 mm Hg)(P < 0.001). The same was observed when we compared the e NOS(56.8 ± 3.7 vs 13.46 ± 2.8 pixels)(P < 0.001),VEGF(34.9 ± 4.7 vs 17.46 ± 2.6 pixels)(P < 0.05),and NTT(39.01 ± 4.0 vs 12.77 ± 2.3 pixels)(P < 0.05) expression by immunohistochemistry of the PPVL animals with the SO group. The expression of e NOS(0.39 ± 0.03 vs 0.25 ± 0.03 a.μ)(P < 0.01) and VEGF(0.38 ± 0.04 vs 0.26 ± 0.04 a.μ)(P < 0.01) were also evaluated by Western blot analysis,and we observed an increase of both proteins on PPVL animals. We also evaluated the DNA damage by comet assay,and observed an increase on damage index and damage frequency on those animals. NAC decreased portal pressure values in PPVL + NAC animals(16.46 ± 2 vs 29.8 ± 1.8 mm Hg)(P < 0.001) when compared to PPVL. The expression of e NOS(14.60 ± 4.1 vs 56.8 ± 3.7 pixels)(P < 0.001),VEGF(19.53 ± 3.2 vs 34.9 ± 4.7 pixels)(P < 0.05) and NTT(21.84 ± 0.7 vs 39.01 ± 4.0 pixels)(P < 0.05) evaluated by immunohistochemistry were also reduced in PPVL + NAC animals. Also,when evaluated by Western blot e NOS expression(0.32 ± 0.03 vs 0.39 ± 0.03 a.μ)(P < 0.05) and VEGF expression(0.31 ± 0.09 vs 0.38 ± 0.04 a.μ)(P < 0.01). Furthermore,NAC modulated DNA damage in PPVL + NAC animals.CONCLUSION: In view of these results,we believe NAC is able to protect the stomach from the alterations induced by the PPVL procedure. AIM: To evaluate the antioxidant effect of N-acetylcysteine ​​(NAC) on the stomach of rats with portal hypertension. METHODS: Twenty-four male Wistar rats weighing ± 250 g were divided into four experimental groups (n = 6 each): Sham- treated with NAC in a dose of 10 mg / kg (ip) diluted in 0.6 m L of saline solution administered administered for 7 d (SO), SO + NAC, partial portal vein ligation (PPVL), and PPVL + starting 8 d after the surgery. Animals from the PPVL and SO group received saline solution (0.6 m L) for the same period of time as the PPVL + NAC and SO + NAC group. On the 15 th day the animals were anesthetized and we We performed the immunohistochemical analysis for endothelial nitric oxide synthase (e NOS), vascular endothelial growth factor (VEGF), and nitrotirosine (NTT) proteins in stomach. We also evaluated eNOS and VEGF by Western blot analysis and assessed DNA dam age in blood samples by the comet assay .RESULTS: The portal hypertension group showing increases in portal pressure when compared to SO group (29.8 ± 1.8 vs 12.0 ± 0.3 mm Hg) (P <0.001). The same was observed when we compared the eNOS (56.8 ± 3.7 vs 13.46 ± 2.8 pixels) (P <0.001), VEGF (34.9 ± 4.7 vs 17.46 ± 2.6 pixels), and NTT (39.01 ± 4.0 vs 12.77 ± 2.3 pixels) 0.05) expression by immunohistochemistry of the PPVL animals with the SO group. The expression of eNOS (0.39 ± 0.03 vs. 0.25 ± 0.03 a.μ) (P <0.01) and VEGF (0.38 ± 0.04 vs 0.26 ± 0.04 a.μ) (Also P <0.01) were also evaluated by Western blot analysis, and we observed an increase of both proteins on PPVL animals. We also evaluated the DNA damage by comet assay, and observed an increase on damage index and damage frequency on those animals. decreased portal pressure values ​​in PPVL + NAC animals (16.46 ± 2 vs. 29.8 ± 1.8 mm Hg) (P <0.001) when compared to PPVL. The expression of eNOS (14.60 ± 4.1 vs 56.8 ± 3. 7 pixels) (P <0.001As (19.53 ± 3.2 vs 34.9 ± 4.7 pixels) (P <0.05) and NTT (21.84 ± 0.7 vs 39.01 ± 4.0 pixels) (P <0.05) as compared to PPVL + NAC animals evaluated by Western blot eNOS expression (0.32 ± 0.03 vs 0.39 ± 0.03 a.μ) (P <0.05) and VEGF expression (0.31 ± 0.09 vs 0.38 ± 0.04 a.μ) (P <0.01) damage in PPVL + NAC animals.CONCLUSION: In view of these results, we believe NAC is able to protect the stomach from the alterations induced by the PPVL procedure.