| Part ?: The effect of nitrate on rat dorsal random flap and its mechanism Objective: To observe the effect of oral nitrate on the survival of rat dorsal random flap and to explore its possible mechanism.Methods: The modified McFarlane rat dorsal random skin flap was used to make the model.Twenty-four healthy adult male rats were randomly divided into 3 groups: the control group,the NaCl group,and the nitrate group.The nitrate group was given 0.5mmol/L sodium nitrate 7 days before operation and daily after operation,the NaCl group was given the same amount of sodium chloride daily,and the control group was given distilled water daily.The survival area of the flap was observed on the 1st,3rd and 7th postoperative days,and the blood perfusion of the flap was measured.On the 7th day after operation,the contents of serum nitrate and nitrite in rats were detected,and the levels of TNF-? and IL-6 in serum were further detected.Meanwhile,histological changes of skin flap were observed and neovascular density was measured.Results: The survival rate and blood perfusion of the flap in the experimental group were significantly higher than those in the control group on the 3rd and 7th days after operation(P<0.05).On the 7th day after operation,the serum nitrate and nitrite contents were significantly higher than those in the control and NaCl group(P<0.05).HE staining and immunohistochemical staining showed that compared with the control group and the NaCl group,the flap structure of the Nitrate group was complete,the inflammatory exudates were reduced,and the microvascular density was increased(P<0.05).In addition,the microvascular density in the experimental group was significantly higher than that in the control group(P<0.05).The levels of TNF-? and IL-6 in serum in Nitrate group were significantly lower than those in Control group and NaCl group(P<0.05).Conclusion: Oral nitrate can improve the survival rate of random flap in rats by restoring blood flow of ischemic tissue,promoting angiogenesis and reducing circulating inflammatory factors.Part ?: Effects of Nitrate on Ischemia Reperfusion Injury of Rat Flap and Its Mechanism Objective: To observe the effect of nitrate on ischemia-reperfusion injury of rat skin flap and explore its potential mechanism from the perspective of oxidative stress and inflammatory response.Methods: Rats in each group were prepared with 3cm×4cm island flaps pedicled with lumbar iliac artery and vein on the back.Thirty-two rats were randomly divided into sham group,ischemia reperfusion group,normal saline group and nitrate group.Rats in ischemia-reperfusion group,normal saline group and nitrate group underwent 10 h ischemia and 12 h reperfusion,while rats in sham operation group were not subjected to ischemia and reperfusion.The nitrate group was given 0.5mmol/L sodium nitrate 7 days before operation and 0.5 mmol/L sodium nitrate after operation,the normal saline group was given the same amount of sodium chloride every day,and the sham operation group and ischemia reperfusion group rats were given distilled water every day.After reperfusion for 12 hours,the activities of oxidation and antioxidant markers in flap tissue were detected,and the levels of inflammatory factors TNF-? and IL-6 were further detected.In addition,HE staining was used to observe the structural changes of the flap tissue,TUNEL staining was used to detect the apoptosis index in the flap tissue,and immunohistochemistry was used to observe the inflammatory cell infiltration in the flap tissue.Results: Most or all of the flap based on the left iliac and lumbar artery was necrotic after ischemia reperfusion injury.After nitrate treatment,the necrosis of the flap was significantly improved.HE stained light microscopy showed that compared with the IR group and IR + NaCl group,the layers of the flap tissue in the IR + Nitrate group were clear in structure,and cell degeneration and necrosis were rare.TUNEL staining and immunohistochemical staining showed that the skin flap apoptosis rate and inflammatory cell infiltration in the IR and IR + NaCl groups were significantly higher than those in the Sham group(P<0.05),and the skin flap apoptosis rate and inflammatory cell infiltration in the IR + Nitrate group were significantly reduced(P<0.05).The content of TNF-?,IL-6 and MDA in the flap tissue of IR + Nitrate group was significantly lower than that of IR group and IR + NaCl group(P<0.05),while the SOD activity was significantly higher than that of IR group and IR + NaCl group(P<0.05).Conclusion: Nitrate can effectively protect skin flap against ischemia-reperfusion injury.This protection by nitrate is related to effectively enhance antioxidant activity,reduce lipid peroxidation in tissues and inhibit inflammatory response during ischemia-reperfusion period. |
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