Whole-body distribution of 11C-(4)-L-aspartic acid in rats

Enzymatic synthesis of 11C-(4)-L-aspartic acid was undertaken using commercially available wheat germ phosphoenolpyruvate carboxylase. Whole-body distribution of the radioactive compound in rats showed higher accumulation in the salivary gland, glandular stomach and the pancreas, as well as in the lungs. Within 60 minutes after intravenous injection of 11C-(4)-L-aspartic acid, about 60% is removed as 11CO2 by expiration, indicating that the carbon atom at the fourth position of the radioactive compound is easily subjected to decarboxylation.