INCORPORATION OF [1-CARBON-11]PALMITATE IN MONKEY BRAIN USING PET

We determined regional incorporation coefficients (k) of plasma [1-C- 11]palmitate into stable brain lipids of anesthetized monkeys with PET . Methods: Carbon-11-palmitate was injected intravenously in untreated animals and in animals pretreated with methyl palmoxirate (MEP), an i nhibitor of beta-oxidation of palmitate in the brain and periphery. Pl asma radioactivity was followed, and brain radioactivity was determine d at various times using PET. A least-squares method was used to fit t he data to an operational equation to obtain regional values of k and of cerebral blood volume (V-b) in individual experiments. Results: ME P significantly decreased the integral of plasma [C-11]CO2 following C -11-paalmtate infusion. Mean values of k in monkeys not given MEP wer e 4.9, 4.2, 4.9, 4.0 and 2.9 x 10(-5) ml/sec g for the temporal, front al, parietal and occipital cortices and white matter, respectively. Wi th the exception of k in white matter, which was increased by MEP, k* in the other brain regions was not significantly changed by MEP. The V-b ranged from 0.035 ml/g to 0.048 ml/g in gray matter regions and eq ualed 0.022 ml/g in white matter. Conclusion: PET can be used to deter mine regional incorporation coefficients of C-11-palmitate into the pr imate brain in vivo. Combined with MEP, C-11-palmitate could be used w ith PET to examine regional brain phospholipid metabolism in humans in normal and pathological conditions.