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EFFECT OF EXERCISE ON GLUTAMINE SYNTHESIS AND TRANSPORT IN SKELETAL MUSCLE FROM RATS
Author(s) -
Dos Santos Ronaldo VT,
Caperuto Érico C,
De Mello Marco T,
Batista Jr Miguel L,
Rosa Luis FBPC
Publication year - 2009
Publication title -
clinical and experimental pharmacology and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 103
eISSN - 1440-1681
pISSN - 0305-1870
DOI - 10.1111/j.1440-1681.2009.05146.x
Subject(s) - glutamine , medicine , endocrinology , sed , skeletal muscle , insulin , chemistry , soleus muscle , biology , biochemistry , amino acid
SUMMARY1 Reductions in plasma glutamine are observed after prolonged exercise. Three hypotheses can explain such a decrease: (i) high demand by the liver and kidney; (ii) impaired release from muscles; and (iii) decreased synthesis in skeletal muscle. The present study investigated the effects of exercise on glutamine synthesis and transport in rat skeletal muscle. 2 Rats were divided into three groups: (i) sedentary (SED; n = 12); (ii) rats killed 1 h after the last exercise bout (EX‐1; n = 15); and (iii) rats killed 24 h after the last exercise bout (EX‐24; n = 15). Rats in the trained groups swam 1 h/day, 5 days/week for 6 weeks with a load equivalent to 5.5% of their bodyweight. 3 Plasma glutamine and insulin were lower and corticosterone was higher in EX‐1 compared with SED rats ( P < 0.05 and P < 0.01, respectively). Twenty‐four hours after exercise (EX‐24), plasma glutamine was restored to levels seen in SED rats, whereas insulin levels were higher ( P < 0.001) and costicosterone levels were lower ( P < 0.01) than in EX‐1. In the soleus, ammonia levels were lower in EX‐1 than in SED rats ( P < 0.001). After 24 h, glutamine, glutamate and ammonia levels were lower in EX‐24 than in SED and EX‐1 rats ( P < 0.001). Soleus glutamine synthetase (GS) activity was increased in EX‐1 and was decreased in EX‐24 compared with SED rats (both P < 0.001). 4 The decrease in plasma glutamine concentration in EX‐1 is not mediated by GS or glutamine transport in skeletal muscle. However, 24 h after exercise, lower GS may contribute to the decrease in glutamine concentration in muscle.