Uptake kinetics of 14C L-leucine and 14C L- and 14C D-methionine in rat brain and incorporation into protein.

Because the amino acids 11C L-leucine, 11C L-methionine, and 11C D-methionine are used for examinations of brain tumors with positron emission tomography (PET), the uptake of the corresponding 14C substances and their incorporation into protein was studied in the rat brain. The uptake of all three substances from the plasma, across the blood-brain barrier, and into the brain took place quite quickly; return to the plasma seemed negligible. Incorporation into protein took place much more slowly.