Objective: We investigated the effect of supplementation with L-glutamine and L-alanyl-L-glutamine (DIP) on the plasma and tissue glutamine concentrations of exercise-trained rats immediately and 3 hours after a single exercise session until exhaustion.
Methods: Thirty-six male rats were divided into six groups, and then subdivided into groups submitted only to the exhaustion test: control (CON-EXA, n = 6), glutamine (GLN-EXA, n = 6) and DIP-EXA (n = 6), or to the exhaustion test followed by a recovery period lasting 3 hours: control (CON-REC, n = 6), glutamine (GLN-REC, n = 6) and DIP-REC (n = 6). The training protocol consisted of bouts of swimming exercise (60 min x day(-1)) for 6 weeks. During the last 21 days, before sacrifice, the glutamine and DIP groups received a daily dose of 1 g x kg(-1) of glutamine and 1.5 g x kg(-1) of DIP, respectively. The GLN-REC and DIP-REC groups were also supplemented immediately after the exhaustion test. Concentrations of glutamine, glutamate, glucose and ammonia in plasma and of glutamine, protein and glycogen in liver and muscle were evaluated.
Results: The time to exhaustion did not differ between groups. A higher concentration of glutamine in the gastrocnemius and soleus muscles was observed for the DIP-EXA group compared to the CON-EXA and GLN-EXA groups (P < 0.05). The DIP-REC group presented a higher plasma and liver glutamine concentration than the CON-REC group (P < 0.05). Muscle glutamine and protein concentration was higher in both the GLN-REC and DIP-REC groups compared to the CON-REC group (P < 0.05).
Conclusions: Chronic supplementation with DIP promoted a higher muscle glutamine concentration than chronic supplementation with glutamine immediately after exercise. However, no significant difference in plasma or tissue glutamine concentrations was observed between acute supplementation with glutamine and DIP during the post-exhaustive exercise recovery period.