Changes in alanine transaminase activity in several organs of the rat induced by a 24-hour fast

The activity of alanine transaminase in the liver, intestine, stomach, striated muscle, kidneys, adipose tissue, brain and skin of fed and 24-hours fasted adult rats has been determined. The range of activities expressed per unit of protein and DNA weight is rather similar in most organs, with highest values for the liver enzyme. Fasting induced significant increases mainly in peripheral organs, with a combined 35% increase, whereas the liver capability actually decreased by 14% because of the decrease in liver size; and all other splanchnic extrahepatic tissues activity studied increased by 22%. The results obtained agree with the postulated activity of the glucose-alanine cycle under these conditions of fasting.