Transport of cis- and trans-4-[ 18F]fluoro-L-proline in F98 glioma cells

The transport mechanisms of cis-4-[ 18F]fluoro-L-proline (cis-FPro) and trans-4-[ 18F]fluoro-L-proline (trans-FPro) were studied in F98 rat glioma cells in comparison to the natural parent [ 3H]-L-proline. Uptake rates of cis-FPro and trans-FPro in F98 glioma cells were 50–70% lower than those of [ 3H]-L-proline. The amino transport system A inhibitor MeAIB reduced the uptake of [ 3H]-L-proline by 30% and uptake of cis-FPro by 46% while uptake of trans-FPro was not significantly changed. BCH inhibited the uptake of all tracers by 35–44%, serine by 70–90% and L-proline by 60 –80%. Absence of Na + reduced uptake of all tracers significantly but no further inhibitory effect could be observed which suggests a component of unspecific uptake. Radioactivity of cis- and trans-FPro in the acid precipitable fraction was