Intestinal intraluminal injection of glutamine increases trolox total equivalent antioxidant capacity (TEAC) in hepatic ischemia-reperfusion

PURPOSE: To evaluate the effects of intraluminal injection of glutamine on the serum trolox equivalent antioxidant capacity in an experimental model of ischemia-reperfusion of the liver observing the applicability of modifications on the original assay method. METHODS: Thirty Wistar rats underwent laparotomy to perform a 20 cm blind sac of small bowel and occlusion of the hepatic hilo for 30 minutes and reperfusion for 5 minutes. Into the gut sac it was injected glutamine (glutamine group, n=10) or distilled water (control group, n=10). Ten other animals (sham group) underwent laparotomy without artery occlusion. Blood samples were collected for trolox equivalent antioxidant capacity assays in different temperature conditions, reagent quantities and time for spectrophotometer readings. RESULTS: Total antioxidant capacity was significantly greater in glutamine group than in both control group (1,60[1,55-1,77] vs 1,44[1,27-1,53]) and sham group (1,60[1,55-1,77] vs 1,48[1,45-1,59]). CONCLUSION: Glutamine enhanced serum antioxidant capacity. The assay technique consistently reflected the changes in the antioxidant defenses in this experimental model.

OBJETIVO: Avaliar em um modelo experimental de isquemia-reperfusão hepática os efeitos da injeção intraluminal de glutamina na capacidade anti-oxidante total em equivalência ao trolox (TEAC) do plasma, verificando a aplicabilidade de modificações ao método original de dosagem. MÉTODOS: Trinta ratos Wistar foram submetidos a laparotomia e confecção de uma alça fechada de 20 cm de comprimento envolvendo o intestinal delgado distal seguido do clampeamento do hilo hepático por 30 minutos e reperfusão por 5 minutos. Na alça fechada foi injetada glutamina (grupo glutamina; n=10) ou água destilada (grupo controle; n=10). Em dez animais (grupo sham) não foi realizado clampeamento hilar. Coletou-se sangue para dosagem da capacidade antioxidante total em equivalência ao trolox em condições modificadas de temperatura, proporções relativas dos reagentes e tempo de leitura sob espectrofotometria. RESULTADOS: A capacidade antioxidante total foi significantemente maior (p<0.05) no grupo glutamina que no grupo controle (1,60[1,55-1,77] vs 1,44[1,27-1,53]) e grupo sham (1,60[1,55-1,77] vs 1,48[1,45-1,59]). Não houve diferenças estatísticas entre o grupo controle e o grupo sham. CONCLUSÃO: A glutamina melhorou a capacidade anti-oxidante total plasmática. O método de dosagem refletiu consistentemente alterações na defesa anti-oxidante nesse modelo experimental.

A comparison of methods employed to evaluate antioxidant capabilities

Three different methodologies frequently employed to evaluate the indexes that report the antioxidant capabilities of pure compounds and/or complex mixtures of antioxidants are applied to a series of mono- and polyphenols, as well as to two wine (red and white) samples. These methodologies are based on the bleaching of a stable radical, the effect of the additive upon luminol chemiluminescence induced by peroxyl radicals, and the effect of the additive upon the bleaching of the fluorescence from a dye molecule. Widely different responses are obtained from the different methodologies. These differences are interpreted in terms of the different factors (stoichiometric factors and/or reactivities) that determines the indexes evaluated by these different methodologies.