Impact of intestinal ischemia/reperfusion on free amino acid levels in plasma / 中华临床营养杂志

ABSTRACT

Objective To investigate intestinal mucosal injury and the change of free amino acid levels in plasma with intestinal ischemia/reperfusion.Methods Twenty-four Sprague-Dawley (SD) male rats (SPF grade) were randomly divided into 3 groups with 8 rats in each group:Blank group,Sham group and ischemia/reperfusion (I/R) group.The rats in I/R group were subjected to 60 min ischemia by clamping the superior mesenteric artery (SMA),followed by 120 min repeffusion.All rats were sacrificed with blood withdraw through inferior vena cava.The plasma was precipitated with Sulfosalicylic acid and the supernatant free amino acid levels were measured and the intestinal mucosal thickness and villus length were also assayed.Results In the I/R group the total free amino acids,essential amino acids (EAA),glutamine and branched-chain amino acids (BCCA) were remarkably lower [the total free amino acids:I/R vs Blank vs Sham:(4585.1 326.1) vs (5661.5 ±581.9) vs (5337.9±998.7) μmol/L (F=5.075,P=0.016); EAA:I/Rvs Blank vs Sham:(1401.3 ±183.4) vs (2147.6 ± 265.1) vs (1796.2 ± 440.8) μmol/L (F =1 1.216,P =0.000) ; glutamine:I/R vs Blank vs Sham:(646.1 ± 34.7) vs (895.7 ± 258.8) vs (839.1 ± 163.7) μmol/L (F =4.326,P =0.027) ; BCCA:I/R vs Blank vs Sham:(507.8 ± 119.0) vs (912.2 ± 165.8) vs (671.9 ± 79.8) μmol/L (F =10.662,P =0.001)]and the jejunum and ileum mucosal thickness and villus height were decreased compared to Blank and Sham groups [jejunum mucosal thickness:I/R vs Blank vs Sham:(401.50 ± 117.79) vs (529.22 ±54.73) vs (499.54 ±64.48) μm (F=31.869,P =0.000) ; jejunum villus height:I/R vs Blank vs Sham:(271.37 ± 84.29) vs (365.26 ± 46.98) vs (349.67 ± 56.11) μm (F =30.472,P =0.000) ; ileum mucosal thickness:I/R vs Blank vs Sham:(254.20 ± 43.56) vs (324.70 ± 30.56) vs (298.26 ± 58.46) μm (F =30.442,P =0.000) ; ileum villus height:I/R vs Blank vs Sham:(169.37 ± 37.25) vs (221.62 ± 37.26) vs (193.25 ± 38.39) μm (F =24.145,P =0.000)],and The EAA and BCAA in the I/R group were lower than the Sham group (respectively,P ＜0.05).There was no significant difference in aromatic amino acids (AAA) among the three groups [I/R vs Blank vs Sham:(273.2 ± 37.4) vs (296.8 ± 55.6) vs (281.9 ± 7.3) μmol/L (F =0.578,P =0.570)].The ratio BCAA/AAA in the Sham and I/R groups were significantly lower than the Blank group [(I/R vs Blank vs Sham:(2.4 ±0.6) vs.(1.9 ±0.4) vs (3.1 ±0.7) (F =5.215,P =0.014)],while the I/R group was decreased slightly compared to the Sham group,but the difference was not significant (P ＞ 0.05).The ethanolamine phosphate,taurine,citrulline,cystine,phosphoserine levels were reduced in the Sham and I/R groups compared to the Blank group [ethanolamine phosphate:I/R vs Blank vs Sham:(11.4 ± 1.9) vs (14.3 ± 3.4) vs (10.1±1.7) μmol/L(F=5.897,P=0.009);taurine:I/R vs BlankvsSham:(341.1±36.3) vs(533.2±90.8) vs (439.2±105.4) μmol/L (F=10.702,P=0.001); citrulline:I/R vs Blank vs Sham:(57.7±3.2) vs (73.1 ±16.2) vs (58.1 ±3.8) μmol/L (F=6.360,P =0.007); cystine:I/R vs Blank vs Sham:(20.0 ± 3.6) vs (60.6 ± 24.6) vs (36.3 ± 5.8) μmol/L (F =15.344,P =0.000) ; phosphoserine:I/R vs BlankvsSham:(10.2±1.1) vs (15.8±5.4) vs (11.7 ±3.4) μmol/L (F=4.878,P=0.018)],and the taurine and cystine in I/R groups were significantly decreased than the Sham group (respectively,P ＜ 0.05).The ornithine and arginine were comparatively reduced in I/R in contrast to the Blank and Sham groups [ornithine:I/R vs Blank vs Sham:(81.5 ± 19.0) vs (125.5 ±42.3) vs (114.9 ± 19.5) μmol/L (F =4.961,P =0.017) ;arginine:I/R vs Blank vs Sham:(199.2 ± 8.0) vs (258.9 ± 14.6) vs (248.7 ± 38.4) μmol/L (F =13.940,P =0.000)].The tryptophan and glutamic acid concentrations were increased in the Sham and I/R groups [tryptophan:L/R vs Blank vs Sham:(125.9 ± 12.1) vs (103.1 ± 29.9) vs (128.9 ± 18.5) μmol/L (F =5.429,P =0.031) ; glutamic acid:I/R vs Blank vs Sham:(188.6 ± 29.8) vs (93.6 ± 29.4) vs (125.4 ± 43.8) μmol/L (F =15.241,P =0.000)] and it was lower in the Sham group than the I/R group (P ＜ 0.05).Conclusion Intestinal ischemia-reperfusion can cause intestinal mucosal injury and the change of free amino acid levels in plasma and intestinal barrier damage may be related to the decline glutamine concentration and the increase of protein catabolism.