Incorporation of [1-carbon-11]palmitate in monkey brain using PET.
We determined regional incorporation coefficients (k*) of plasma [1-11C]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 inhibitor of beta-oxidation of palmitate in the brain and periphery. Plasma radioactivity was followed, and brain radioactivity was determined at various times using PET. A least-squares method was used to fit the data to an operational equation to obtain regional values of k* and of cerebral blood volume (Vb) in individual experiments.


RESULTS
MEP significantly decreased the integral of plasma [11C]CO2 following 11C-palmitate infusion. Mean values of k* in monkeys not given MEP were 4.9, 4.2, 4.9, 4.0 and 2.9 x 10(-5) ml/sec.g for the temporal, frontal, parietal and occipital cortices and white matter, respectively. With 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 Vb ranged from 0.035 ml/g to 0.048 ml/g in gray matter regions and equaled 0.022 ml/g in white matter.


CONCLUSIONS
PET can be used to determine regional incorporation coefficients of 11C-palmitate into the primate brain in vivo. Combined with MEP, 11C-palmitate could be used with PET to examine regional brain phospholipid metabolism in humans in normal and pathological conditions.
Laboratory of Neurosciences, National Institutes on Aging, National Institutes of Health, Bethesda, MD 20892, USA.
T
T
Arai
S
S
Wakabayashi
M A
MA
Channing
B B
BB
Dunn
M G
MG
Der
J M
JM
Bell
P
P
Herscovitch
W C
WC
Eckelman
S I
SI
Rapoport
M C
MC
Chang
D000818:Animals; D001921:Brain / Q000000981:diagnostic imaging* / Q000378:metabolism; D002250:Carbon Radioisotopes / Q000493:pharmacokinetics; D002560:Cerebrovascular Circulation; D004852:Epoxy Compounds / Q000494:pharmacology; D008253:Macaca mulatta; D008297:Male; D008962:Models, Theoretical; D019308:Palmitic Acid; D010169:Palmitic Acids / Q000493:pharmacokinetics; D011292:Premedication; D011422:Propionates / Q000494:pharmacology; D014055:Tomography, Emission-Computed
D002250:Carbon Radioisotopes; D004852:Epoxy Compounds; D010169:Palmitic Acids; D011422:Propionates; D019308:Palmitic Acid; C017522:methyl 2-tetradecylglycidate