| Objective To evaluate the feasibility of rat superficial inferior epigastric artery (SIEA)flap as an ischemia/reperfusion model, and explore new methods for fixing andprotecting flaps; To observe the effects of edaravone on ischemia/reperfusion injury inrat skin flaps, explore the possible mechanism from the view of scavenging oxygenradicals; Further investigated the effects of edaravone on microcirculation of rat skinflaps which suffered ischemia/reperfusion injury, and explored the possible mechanismfrom the view of maintaining blood vessels of microcirculation.Methods Part I: Sixteen adult SD rats were randomly divided into2groups: controlgroup(n=8), experimental group (n=8). A left low abdominal island flap which sized6.0cm x3.0cm and fed by the superficial epigastric artery was created in rats of all the2groups. Dissected and observed blood vessels of the pedicle, blocked the arterial bloodflow by vascular clamps for10hours to establish ischemia/reperfusion model of flaps.Rats in experimental group were fixed with a holding device but rats in control groupnot. Survival situation, retraction of flaps and preventive effect of the holding devicewere observed daily for5days. Part II: Forty-eight SD rats were randomly divided into3groups: control group(n=16), ischemia/reperfusion group (IR group)(n=16), andEdaravone treated IR group(n=16). A left low abdominal island flap which sized6.0cmx3.0cm and fed by the superficial epigastric artery was created in rats of all the threegroups. Flaps of IR group and Edaravone treated IR group were blocked the arterialblood flow by vascular clamps for10hours. From15mins before reperfusion, rats inEdaravone treated IR group were intraperitoneally injected edaravone dilutions [10mg/(kg·12h)] for three days; Rats in IR group and control group were intraperitoneallyinjected saline with the same frequency and volume to rats in the Edaravone treated IR group. In IR group and Edaravone treated IR group, full-thickness of the flaps wereharvested respectively when the flaps were reperfused24hours. In control group, thesamples of flaps were harvested when the flaps were created34hours after theoperation. Content of malondialdehyde (MDA) and activity of superoxide dismutase(SOD) were respectively detected by the test kits. The structural changes andinflammatory cells infiltration of flaps were observed through HE stain with lightmicroscope. Seven days after the operation, the flap viability of three groups wereobserved and calculated. Part III: Twenty-four SD rats were randomly divided into3groups: control group (n=8), IR group (n=8), and Edaravone treated IR group(n=8).Modeled and drug intervention as Part II. In IR group and Edaravone treated IR group,full-thickness of the flaps were harvested respectively when the flaps were reperfused24hours. In control group, the samples of flaps were harvested when the flaps werecreated34hours after the operation. Apoptosis of vascular cells were detected byterminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assay (TUNELassay), then calculated the apoptotic ratio of vascular cells. In IR group and Edaravonetreated IR group, ultrastructural changes of vascular endothelial cells were observed bytransmission electron microscopy. Seven days after the operation, marked the bloodvessels of flaps by immunohistochemical stain in the three groups and calculated theaverage number of blood vessels subcutaneously.Results Part I: We confirmed that SIEA flap is fed sufficiently by superficial inferiorepigastric artery, the superficial inferior epigastric artery is easy to dissected for itssuperficial and constant location，and long vascular pedicle make the handle of bloodvessels easy. Observed flaps after two days, three days and five days of the operationrespectively, we found that the holding device was benefit to protect flaps and preventretraction of flaps. Part II: The content of MDA and interstitial multicore inflammatorycells count in Edaravone treated IR group were significantly lower than that in IR group;The content of MDA and interstitial multicore inflammatory cells count in controlgroup were significantly lower than that in Edaravone treated IR group and IR group;The activity of SOD and flap viability in Edaravone treated IR group were significantly higher than that in the IR group; The activity of SOD and flap viability in control groupwere significantly higher than that in the Edaravone treated IR group and IR group. Allthe differences were statistically significant. Part III: The apoptotic ratio of vascularcells in Edaravone treated IR group was significantly lower than that in IR group; Theapoptotic ratio of vascular cells in control group was significantly lower than that inEdaravone treated IR group and IR group; The average number of blood vesselssubcutaneously in Edaravone treated IR group was significantly higher than that in theIR group; The average number of blood vessels subcutaneously in control group wassignificantly higher than that in the Edaravone treated IR group and IR group. All thedifferences were statistically significant. The injury degree of ultrastructure in vascularendothelial cells was lower in Edaravone treated IR group than that in the IR group.Conclusion SIEA flap is feasible for the study of ischemia/reperfusion injury in rats.The new holding device can make up for disadvantages of plaster fixation and has anumber of advantages that plaster fixation does not have. The holding device can beused as a new method to promote in animal experiments. Edaravone can enhance theviability of flaps suffered ischemia/reperfusion injury, which is related to scavengingfree radicals, reducing the extent of lipid peroxidation and inflammation in the earlystages of reperfusion. In the course of ischemia/reperfusion, microcirculation is criticalto the survival of flaps. Reducing the apoptotic ratio of vascular cells, protecting thestructure and function of vascular endothelial cells, more effectively maintaining theaverage number of blood vessels subcutaneously may be one of the mechanisms thatedaravone protect microcirculation of flaps. |
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