丙胺酰-谷氨酰胺预处理对大鼠体外循环后肠黏膜屏障功能的影响

The effects of pretreatment with alanyl-glutamine dipeptide on intestinal barrier function in rats after cardiopulmonary bypass

目的 观察丙胺酰-谷氨酰胺（Ala-Gln）预处理对大鼠体外循环（CPB）后血浆和肠黏膜二胺氧化酶（DAO）活性,血浆D-乳酸及脂多糖（LPS）浓度的影响,探讨Ala-Gln对肠屏障功能的保护作用.方法 健康成年雄性清洁级SD大鼠60只,随机分为3组,每组20只：实验组（G组,丙胺酰-谷氨酰胺预处理后行CPB）,CPB对照组（CPB组）、假手术组（SH组,仅在各部位进行插管操作,不转流）.分光光度法测定DAO活性和血浆D-乳酸浓度.过氯酸新法预处理,血浆鲎试剂显色法测定血浆内毒素浓度.结果 与SH组相比,G组和CPB组血浆中DAO活性、D-乳酸浓度、LPS浓度显著升高,肠黏膜组织中DAO活性显著降低,差异均有统计学意义（P＜0.05）.与CPB组相比,G组血浆DAO活性、D-乳酸浓度、LPS浓度显著降低,差异均有统计学意义（P＜0.05）;G组肠黏膜组织中DAO活性高于CPB组,但差异无统计学意义（P =0.065）.结论 Ala-Gln预处理能降低肠通透性,是体外循环肠黏膜屏障功能保护的新途径.

Objective To explore the protective effects of pretreatment with alanyl-glutamine dipeptide on intestinal barrier function in rats after cardiopulmonary bypass.Methods CPB model in rats was established.60 SD rats were randomly divided into group G（pretreatment with alanyl-glutamine before CPB for 3 days and primed with it during CPB,n =20）,group CPB（n =20） and sham-operation（SH） group（n =20）.The diamine oxidase（DAO） activity of plasma and tissue homogenate of intestinal mucosa were measured by spectrophotometry,and the concentration of plasma D-lactate was also detected by spectrophotometry.The levels of plasma lipopolysaccharide（LPS） was measured by tachypleus amebocyte lysate development process.And software SPSS 16.0 was used for statistics analysis.Results The plasma DAO activity in group G was significantly lower than that in group CPB（P 〈0.05）,even though compared with group SH,the DAO activity in group G and CPB were significantly increased （P 〈 0.05）.The activity of DAO in tissue homogenate in group G and CPB were decreased more significantly than that in group SH（P 〈 0.05）,but there was no difference between group G and CPB （P =0.065）.The plasma concentrations of D-lactate and LPS in group G were significantly lower than that in group CPB （P 〈 0.05）,and the plasma concentration of D-lactate and LPS in both group G and CPB were markedly enhanced compared with group SH（P 〈 0.05）.Conclusion Precondition with alanyl-gluamine dipeptide can decrease the permeability of gut mucosa,and might be a new way to protect the intestinal barrier function during cardiopulmonary bypass.