Abstract
The amino acid 75Se-L-selenomethionine was used to study variations in amino acid uptake by various tissues of rats and mice adapted to a schedule of controlled feeding and lighting conditions. Food only became available for an 8-hour period at the beginning of the 12-hour dark period of the 24-hour cycle. Systematic oscillations were observed in the uptake of selenomethionine by the liver, pancreas, blood, kidneys, skeletal muscle, bone and brain of both rats and mice but only very small changes were noted in the spleen, lung and heart. The level of the uptake into the liver and pancreas and possibly the kidney appear to be related to the dietary state of the animals.