Effects Of Silver-nylon With Weak Direct Current On Inducible Nitric Oxide Synthase Before And After The Healing Of Partial-Thickness Scald Wound On Guinea Pigs

BackgroundProf.Zhu Zhisheng from the U.S.Army Institute of Surgical Research developed a new way to treat burn wounds by applying silver-nylon dressings with weak direct current(SNDC) in 1988.Since 2003, Department of Burns,The Second Affiliated Hospital, Zhejiang University school of Medicine was the first at home to repeat zhu's study by treating partial-thickness scalded(10% of their body surface area, 10%TBSA) guinea pigs with SNDC and proved that SNDC can improve the healing of burn wound.Furchgott and Zawadski first found that endotheliocyte can secrete substance which causes vasodilation and named it endothelium derived relaxing factor in 1980. And Palmer confirmed that it is nitric oxide(NO).No is produced from L-arginone by the catalysis of nitricoxide synthase(NOS). NOS is the key enzyme of the synthesization of NO.There are two kinds, constitutive NOS (cNOS ) and inducible NOS ( iNOS ) .cNOS depends on Ca2+/CaM and isn't induced by endotoxin,while iNOS is on the contrary. According to many reports,NO increased in the body of animals and human after burned or wounded and it could promote the healing of the wound.This experiment aimed to study the effects of SNDC on changing of iNOS before and after the healing of partial-thickness scald wound on guinea pigs.Materials and MethodsWhite guinea pigs were used as experiment animals,which weighed 285±25g.Then 10% TBSA partial-thickness scald wounds were caused on their backs and randomly divided into two groups.In the control group(SN group,N=30), silver-nylon dressing were immediately applied on the partial-thickness scalding wound. Animals were killed at the lst,2nd,3rd,4th ,8-12* weeks after wounded ,five at a time. One specimen was took from the skin and wound of every killed animal and was made into paraffin block. The experiment group (SNDC group, N=30) were the same as the contral group except that they were applied with 40 uADC,which lasted 96 hours. Animals were killed at the l*^^*, 8-12* weeks after wounded , 5> 5^ 5> 4^ 6 animals respectively. One specimen was took from the skin and wound of every killed animal and was made into paraffin block. The content of iNOS in the total 50 specimens was measured by immunohistochemical analysis.The outcome was marked as (+~+++) to (-).Results(l)iNOS expressed cells mostly distributed in the epidermis and the epithelium of glands. Epidermis lost in deep second degree burned wound,so the expression of iNOS was less in the wound than in the skin at the edge of the wound.(2)iNOS expressed in the control group, 18/20 during 1-4* weeks after wounded and 2/5 during 8-12 weeks, 15/19 during 1-4 weeks and 3/6 during 8-12* weeks in the experiment group. In the control group,the expression of iNOS during 1-4* weeks was higher than that during 8-12* weeks.The difference was statistical significance (P=0.038) .In the experiment group, there's no significant difference (P=0.298) between 1-4* weeks and 8-12* weeks. There's no significant difference (P=0.568) between 1-4* weeks in the experiment group and 8-12* weeks in the control group.ConclusionExpression of iNOS in the skin of guinea pigs increased after partial-thickness scalded and it decreased when the wound healed. SNDC treatment could alter this tendence.