喂饲左旋精氨酸对烫伤大鼠肠道保护作用机制的研究

目的探讨喂饲左旋精氨酸(L-Arg)对烫伤大鼠肠道缺血再灌注损伤的作用机制。方法将66只SD大鼠随机分为正常对照组(6只,不作烫伤和其他处理)、精氨酸组(30只,烫伤后2h喂饲70g/LL-Arg,1ml/次,2次/d)和普通喂养组(30只,烫伤后喂饲等量凉开水)。检测正常对照组及两组烫伤大鼠伤后6、12、24、48、72h肠组织内皮素(ET)水平、一氧化氮(NO)含量、ET/NO比值以及血浆内毒素水平的变化,并取回肠组织标本作病理学观察。结果伤后6、12、24h,精氨酸组大鼠肠组织ET水平分别为(0.80±0.26)、(0.75±0.30)、(0.63±0.22)ng/g,低于普通喂养组(1.26±0.38)、(1.34±0.37)、(0.97±0.19)ng/g(P<0.05);其NO含量显著高于普通喂养组(P<0.01);ET/NO比值和血浆内毒素水平均低于普通喂养组(P<0.05或0.01)。病理学观察显示,精氨酸组大鼠肠黏膜损伤情况明显轻于普通喂养组。结论喂饲L-Arg可减轻烫伤大鼠肠组织缺血再灌注损伤,有利于保护肠黏膜屏障功能。其机制为喂饲L-Arg后增加了肠黏膜局部NO的含量,有助于维持ET/NO比值的稳定。

Study on the mechanism of protective effect of oral L-arginine on intestine after scald injury in rats

OBJECTIVE: To explore the mechanism of protective effect of oral L-arginine (L-Arg) on the intestine after scald injury in rats. METHODS: Sixty-six Sprague-Dawley (SD) rats were randomly divided into three groups: i.e. normal control (N, n = 6, without treatment), oral L-arginine group (A, n = 30, with 1 ml 70 g/L of L-Arg per os 2 times a day from 2 post scald hour (PSH)) on with normal enteral feeding and group B (n = 30, with oral feeding of cold boiled water after scald). The changes in the content of superoxide dismutase (SOD), malondialdehyde (MDA), nitric oxide (NO), endothelin (ET), ET/NO ratio in the intestine and the level of plasma endotoxin (LPS) in portal vein were assessed at 6, 12, 24, 48, 72 PSH. Ileum tissue samples were harvested for pathological examination. RESULTS: The ET content in the intestinal tissue in A group at 6, 12 and 24 PSH (0.80 +/- 0.26 ng/g, 0.75 +/- 0.30 ng/g, 0.63 +/- 0.22 ng/g) was obviously lower than that in B group (1.26 +/- 0.38 ng/g, 1.34 +/- 0.37 ng/g, 0.97 +/- 0.19 ng/g, P < 0.05), but the NO contents in the intestine in A group at the same time points were significantly higher than that in B group (P < 0.01). The ET/NO ratio and the level of plasma endotoxin in A group were significantly lower than those in B group at each time point (P < 0.05 or 0.01). Pathological examination showed that the intestinal mucosal injury in the A group was obviously milder than that in the B group. CONCLUSION: Oral L-arginine was shown to have the effects to ameliorate ischemia reperfusion injury of the intestine and to protect the barrier function of the intestinal mucosa. This might be related to an increase in the NO level in intestinal mucosa resulting in maintenance of a stable ET/NO ratio.