GC–MS analysis of blood for the metabonomic investigation of the effects of physical exercise and allopurinol administration on rats

Exhaustive exercise is a generator of free radicals and reactive species in mammals. Allopurinol is a known inhibitor of xanthine oxidase, a source of free radicals during exercise. In this study, the influence of allopurinol on the metabolic profile of blood plasma of rats that had undergone exhaustive swimming was investigated by GC–MS. Rats were divided into four groups: (i) placebo administration, no exercise; (ii) placebo administration followed by exercise until exhaustion; (iii) allopurinol administration, no exercise; and (iv) allopurinol administration followed by exercise until exhaustion. Samples obtained following the aforementioned treatments were analyzed on GC–MS after two-step derivatization (methoxymation and silylation). GC–MS analysis in full scan acquisition achieved the quantitation of 86 metabolites in 45 min. GC–MS data were analyzed using univariate and multivariate statistical analysis methods. Safe classification/prediction of the samples was accomplished according to exercise and allopurinol administration. Separation of the study groups according to exercise was mainly due to lactic acid, pyruvic acid, 2-hydroxybutyric acid, uracil, oxalic acid, pyroglutamic acid and stearic acid (p < 0.05). Separation according to allopurinol administration was mainly due to compounds of the purine catabolic pathway and amino acids. Allopurinol administration was not found to modulate the metabolic responses to exercise.