休克期切痂对大鼠肺组织ICAM-1、TNF-α　mRNA表达的影响

The effect of escharectomy during burn shock stage on the expression of ICAM-1 and TNF-α mRNA of rat pulmonary tissue

目的研究烧伤后肺组织细胞间粘附分子－１（ＩＣＡＭ－１）、肿瘤坏死因子－α（ＴＮＦ－α）表达和肺组织髓过氧化物酶（ＭＰＯ）活性变化的规律，探讨实施休克期切痂对上述指标变化的影响。方法Ｗｉｓｔａｒ大鼠１７６只，３０％体表面积Ⅲ度烫伤，采用逆转录ｐＣＲ方法分别观察伤后不同时相点及不同时机切痂后肺组织ＩＣＡＭ－１、ＴＮＦ－α ｍＲＮＡ的表达及肺脏 ＭＰＯ活性变化。结果烫伤后肺组织 ＩＣＡＭ－１及 ＴＮＦ－α的 ｍＲＮＡ表达在伤后 ４ ｈ即已升高，分别在伤后１２ ｈ和２４ ｈ达到高峰，伤后 ８ ｈ和 ２４ ｈ切痂组动物切痂后再次出现一峰值，但低于第一个峰值，伤后９６ｈ恢复正常。未切痂组和９６ｈ切痂组在伤后７ｄ仍未恢复正常；休克期切痂动物的肺组织ＭＰＯ活性伤后９６ｈ恢复正常，而非休克期切痂组动物一直维持较高水平。结论尽早切痂去除坏死组织可阻断炎症介质及细菌毒素的释放，避免了内皮细胞大量合成ＩＣＡＭ－１等粘附分子，减轻由粘附分子介导的中性粒细胞对内皮细胞的进一步损害。

Objectives To study the rules of postburn expression of ICAM-1 and TNF-α and the rule of the change in the MPO activity in pulmonary tissue; to explore the influence of escharectomy on the changes in the above indices and to clarify the importance of escharectomy during shock stage. Methods One hundred and seventy six Wistar rats with 30% TBSA Ⅲ degree back scald were used. RT-PCR was used in the examination of the expression of pulmonary tissue ICAM-1 and TNF-α mRNA and of the change in pulmonary MPO activity after escharectomy. Results The expressions of pulmonary ICAM-1 and TNF-α mRNA began to increase at 4 hour postburn and reached peak level at 12 and 24 hours postburn, respectively. Their expressions returned to near control level 96 hours postburn in rats undergone escharectomy during shock stage. On the contrary, they remained at a relative high level even on 7th postburn day in both non-operated rats and the rats receiving escharectomy 96 hours postburn. In addition, pulmonary tissue MPO activity fell to near control level in rats undergone escharectomy during shock stage, but it maintained a high level in rats in which escharectomy was not done during shock stage. Conclusion These findings suggest that eschar could induce the production of endothelial adhesion molecules. Therefore escharectomy as early as possible is very important to prevent the expression and release of adhesion molecules and the development of SIRS.