After synthesis of fluorine-18 labelled analogues by [18F]fluorobenzoylation at the alpha -amino group, biodistribution and elimination of individual advanced glycation endproducts, namely N-epsilon-carboxymethyllysine and N-epsilon-carboxyethyllysine, were studied in comparison to lysine in rats after intravenous injection using positron emission tomography (PET).

The [F-18]radiofluorinatrd amino acids were fast distributed via the blood, followed by a rapid excretion through the kidneys. Elimination kinetics were similar for both AGEs and lysine. For CML and GEL, but not for lysine, a temporary liver accumulation could be observed. which was not connected with any metabolisation or enterohepatic circulation. No further accumulation in any tissues was observable, indicating that increased tissue levels of CML or GEL, which have been described for certain disorders, are exclusively derived from endogenous origin and should nor depend on a dietary intake. However, under uremic conditions, an impaired kidney function might result in a significant increase of the AGE-load of blued and tissues. PET based on F-18-labelled AGEs proved to be a promising tool to elucidate the physiological fate of post-translationally modified amino acids and to clarify the role of AGEs as possible "glycotoxins".