Effect of Alanine on in Vitro Glucose Utilization by Rat Interscapular Brown Adipose Tissue

The rates of either glucose or alanine incorporation into tissue and oxidation to CO2 were studied in rat interscapular brown adipose tissue in order to evaluate the mutual influence of both substrates on their uptake and utilization. Tissue fragments were incubated in vitro in the presence of 1-10 mM glucose and 0.3-1.5 mM alanine. The highest glucose oxidation rate was obtained with the lowest alanine concentrations tested. This suggests that alanine inhibits glucose utilization by this tissue at concentrations that are within the physiological plasmatic range. Glucose levels had little effect upon alanine oxidation, but glucose had a permissive effect on the utilization of alanine. On the basis of these results, it is postulated that this glucose conservation effect of alanine on brown adipose tissue can help to prevent glucose wastage in postprandrial situations.