Acute ethanol administration and the metabolism of glutamine by skeletal muscle of the rat: implications for ethanol-induced reductions in protein synthesis.

The effect of acute ethanol administration (75 mmol/kg) on the metabolism of glutamine by skeletal muscle of the rat was studied in order to investigate the hypothesis that the concentration of this amino acid in muscle controls the rate of protein synthesis. Ethanol administration was without effect on the concentration of glutamine in EDL (extensor digitorum longus) and plantaris muscles (Type II fibre-rich muscles), but increased the concentration in soleus muscle (Type I fibre-rich muscle). The rate of release of glutamine was increased from EDL muscle, but unchanged from soleus muscle of treated animals. Ethanol administration was without effect on the maximal activity of glutamine synthetase in both soleus and EDL muscles. It is concluded that changes in the concentration of glutamine in muscle cannot explain the ethanol-induced changes in the rate of protein synthesis. Nevertheless, the increase in the concentration of glutamine in soleus muscle following ethanol administration is of interest and may be mediated via modulation of the glutamine transporter and/or the activity of glutamine synthetase in vivo.