腹内高压致肠黏膜屏障损伤的实验研究

Experimental study on injury to intestinal mucosal barrier induced by high intraperitoneal pressure

目的观察不同程度腹内压(IAP)及其不同持续时间对兔肠黏膜屏障功能的影响。方法 (1)取9只新西兰兔,制成腹内高压(IAH)模型(IAH模型组),将其IAP分别升至10、20、30 mm Hg(1 mm Hg=0．133 kPa),维持1 h后记录肠黏膜血流量。另检测正常对照组兔(3只)的该项指标。(2)同前分组及设定IAP。维持IAP 1．5 h后,两组兔均以异硫氰酸荧光素-葡聚糖(FITC-D)及Ⅱ型辣根过氧化物酶(HRP-Ⅱ)灌胃。继续维持IAP0．5 h后取两组兔门静脉血,检测FITC-D含量及 HRP-Ⅱ活性。(3)取27只新西兰兔,分组及IAP设定同前,IAH模型组IAP为10、20 mm Hg时,均持续1、2、4 h;IAP为30 mm Hg时,持续1、2 h。抽取各组兔下腔静脉血,检测D-乳酸含量及二胺氧化酶 (DAO)活性;取空肠肠段,常规制作切片,于光学显微镜及透射电镜下观察。结果 (1)IAH模型组兔IAP为10 mm Hg时,其肠黏膜血流量接近正常对照组(P>0．05);IAP为20、30 mm Hg时,肠黏膜血流量分别比正常对照组减少了44％、80％(P<0．01)。(2)IAH模型组兔IAP为10 mm Hg时, 其门静脉血中FITC-D含量接近正常对照组(P>0．05);当IAP为20、30 mm Hg时,分别为正常对照组的4．8、7．0倍(P<0．01)。HRP-Ⅱ的变化趋势与之一致。(3)IAH模型组兔IAP为10 mm Hg时, 各时相点下血浆D-乳酸含量、DAO活性与正常对照组相近(P>0．05);IAP为20、30 mm Hg时,随着压力持续时间的延长,两指标均逐渐升高(P<0．01)。(4)IAP为10 mm Hg持续2 h,IAH模型组兔空肠黏膜轻度水肿;IAP 20 mm Hg持续2 h时,空肠黏膜明显水肿,中央乳糜管扩张,黏膜上皮下间隙扩大;肠上皮微绒毛变短,部分变性、坏死、脱落,线粒体高度肿胀、空泡化。IAP升至30 mm Hg,肠黏膜损伤进一步加重。结论 IAH可导致肠黏膜屏障功能严重受损,这可能是继发全身性炎性反应综合征、脓毒症、腹腔间隙综合征及多器官功能衰竭重要原因。

Objective - To observe the influence of intra-peritoneal pressure for various lengths on intestinal mucosal barrier function. Methods High intraperitoneal pressure was produced by inflation of nitrogen into the rabbits. Totally 51 New Zealand white rabbits were used in the study, and they were randomly divided into following groups ： （ 1 ） IAH 1 （ n = 9, the intestinal mucosal blood flow was determined 1 hour after the intra-abdominal pressure（IAP） reached 10,20 and 30 mmHg, respectively） group, and 3 rabbits were used as normal controls; （2） IAH2 （n = 9, after IAP persisting for 1.5 hours, animals were garaged with FITC-D and HRP-Ⅱ. And 30 minutes later, blood was drawn from portal vein for assessment of intestinal permeability） group; （3） IAH3 （ n = 27,the maintaining time of high pressure was 1,2,4 hours with IAP at 10 and 20 mmHg, and 1, 2 hours with IAP at 30 mmHg） group. D-lactate and diamine oxidase （DAO） levels in portal blood were determined to evaluate intestinal mucosal damages. The histological and ultrastroctural changes in intestinal mucosa were studied with light and electron microscope. Results （ 1 ） When IAP was 10 mmHg, the intestinal mucosal blood flow in IAH1 group was similar to that of normal group（ P 〉0.05）. However, it was 44% and 80% lower than that of normal group when IAP was 20 and 30 mmHg,respectively（ P 〈0.01 ）. （2） When IAP was 10mm Hg in IAH grgttp, the contents of FITC-dextran was similar to that in normal controls（ P 〉 0.05 ） , but it was 4.8 and 7.0 fold of that of controls when IAP was 20 and 30 mmHg,respectively（ P 〈 0.01 ）. Similar changes were found for the contents of HRP-Ⅱ. （3） The plasma contents of D-lactate and DAO when IAP was 10 mmHg in IAH group were similar to that of normal controls at each time points （ P 〉 0.05 ）. But when IAP reached 20 and 30 mmHg, respectively, the contents of these two substances were increased gradually with the lapse of time. （4） Mild edema in jejunal m.ucosa was observed when IAP was maintained at 10 mmHg for 2 hrs. But obvious edema, dilation of central chylous ducts, and widening of submucosal space were observed when IAP was maintained at 20mmHg for 2 hrs, with shortening of enteric villi and denaturation, necrosis and exforliation of a part of them, and serious swelling and vacuolization of mitochondria. The injury of intestinal mucosa was aggravated when IAP was 30 mmHg. Conclusion abdominal hypertension can lead to serious compromise dysfunction of intestinal mucosal barrier, which may be an important factor in developing of ACS and MODS.