Changes in Glutamine, Glutamate and Alanine concentrations after Vaquejada and 3-barrel simulation test on horses

Abstract

Exercise requires intense muscle activity, contributing significantly to protein synthesis and degradation. Few data are reported in the literature for plasma amino acid levels in equine athletes, mainly glutamine (Gln), glutamate (Glu), and alanine (Ala). The aim of this study was to determine the plasmatic Gln, Glu, and Ala concentrations in athlete horses subjected to field simulations of Vaquejada and 3-barrel racing. Twenty-three animals were used, trained, and conditioned, and grouped according to their activity and function as follows: Vaquejada pull horses (G-PUX; n = 12), Vaquejada helper horses (G-AUX; n = 6), and -barrel horses (G-3TB; n = 5). All were from the same training center with the same food management, receiving commercial concentrate divided equally into two meals, water, mineralized salt, and fresh grass ad libitum. Blood samples were collected after overnight fasting by jugular venipuncture with vacuum collection tubes containing heparin and were immediately refrigerated. Samples were collected for each group at different times; G-PUX: rest (T0), immediately after three races (T1), and 15, 30, and 240 min after the third race; G-AUX: rest (T0), immediately after six races (T1), and 15, 30, and 240 min after the sixth race; and G-3TB: rest (T0), immediately after two races (T1), and 15, 30, and 240 min after the last race. After 15 min, the animals had free access to water, mineralized salt, and grass. The heparinized plasma was extracted, acidified, and neutralized as described in the literature, and was later stored and frozen at 20 °C until analysis. The concentration levels of the amino acids were determined enzymatically using a semi-automatic spectrophotometric machine. The data obtained were analyzed using analysis of variance and the Tukey test. The results showed that all the three groups had plasma concentration changes for Ala (p < 0.05), but not for Glu (p > 0.05). In addition, it was observed that only the G-AUX group showed significant changes in Gln concentration, which was high between T-1 and T-240 (p < 0.05). The difference observed between the plasma levels of Gln, Glu and Ala measured are due to the intensity and duration of each physical activity performed in the experimental groups.