卡巴胆碱对烫伤大鼠肠内补液时肠黏膜血流量、Na^＋-K^＋-ATP酶活性和水通道蛋白-1表达的影响

Effects of carbachol on intestinal mucosal blood flow, activity of Na^+-K^+-ATPase and expression of aquaporin-1 during the enteral rehydration of scald rats

目的研究卡巴胆碱对烫伤早期大鼠肠内补液时肠黏膜血流量(IMBF)、Na+-K+-ATP酶活性和水通道蛋白-1(AQP1)表达的影响。方法雄性Wistar大鼠50只,随机分为假烫组、单烫组、肠内卡巴胆碱组、肠内补液组和肠内补液+卡巴胆碱组,每组10只。大鼠经35% TBSA Ⅲ度烫伤后,麻醉状态下进行十二指肠和回肠插管,与输液泵相连形成闭合回路进行小肠补液(灌流)。肠内补液时于烫伤后0.5h开始灌注葡萄糖-电解质溶液,灌注液总量为2ml/(kg.1% TBSA),于3.5h内在智能输液泵控制下匀速输入。卡巴胆碱(60μg/kg)于烫伤后0.5h肠内注射。伤后4h用激光多普勒血流仪测定IMBF,然后处死动物,取肠组织进行Na+-K+-ATP酶活性和AQP1免疫组化测定。结果IMBF、Na+-K+-ATP酶活性和AQP1表达肠内卡巴胆碱组和肠内补液组均显著高于单烫组(P<0.01),但低于肠内补液+卡巴胆碱组(P<0.05)。结论35%TBSAⅢ度烫伤肠内补液时给予卡巴胆碱能增加肠黏膜血流量和Na+-K+-ATP酶活性,促进AQP1表达,有助于肠道对口服液体的吸收。

Objective To investigate the effects of carbachol （a cholinergic agent） on intestinal mucosal blood flow （IMBF）, activity of Na^＋ -K^＋ -ATPase and expression of aquaporin-1 （AQP-1） during enteral rehydration with a glucose electrolyte solution （GES） in scald rats. Methods Fifty male Wistar rats were randomly divided into five groups （10 each） ： sham scald, scald without enteral rehydration, enteral carbachol alone （CAR） after scald, scald with enteral GES （GES） and scald with enteral GES containing carbachol （GES/CAR） groups. About 35% TBSA of scald injury was inflicted on back of all the rats, except those in sham group, with boiling water （100℃, 15s）. 0. 5cm cannula were put into distal duodenum and proximal ileum respectively under anaesthesia, and connected to an infusion pump to form a circulation systerrL Animals were resuscitated with enteral GES （2ml · 1%TBSA^-1 · kg^-1 within 4h post burn） from 0. 5h post injury. Carbachol （60μg/kg） was injected into intestinal lumen at 0. 5h post injury. IMBF was determined by laser Doppler. Animals were sacrificed at 4h after scald, and specimens of gut tissue were taken to examine the activity of Na^＋-K^＋-ATPase and expression of AQP- 1. Results It was found that there were significant decreases in IMBF, activity of Na^＋-K^＋-ATPase and expression of aquaporin-1 in all scald groups compared with that in sham group （P〈0. 01）. Enteral rehydration lead to elevation in IMBF, Na^＋-K^＋ -ATPase and AQP-1 in CAR and GES groups compared with those in scald group （P〈0.01）. The parameters above in GES/CAR group were significantly higher than those in GES and CAR groups （P〈0. 05）. Conclusion The results indicate that carbachol can promote intestinal absorption ability to water and Na^＋ by improving mucosal blood flow, ATPase activity and AQP-1 expression in gut mucosa during enteral rehydration of scald injury in rats.