Brain incorporation of [1-11C]arachidonate in normocapnic and hypercapnic monkeys, measured with positron emission tomography.
Positron emission tomography (PET) was used to determine brain incorporation coefficients k* of [1-11C]arachidonate in isoflurane-anesthetized rhesus monkeys, as well as cerebral blood flow (CBF) using [15O]water. Intravenously injected [1-11C]arachidonate disappeared from plasma with a half-life of 1.1 min, whereas brain radioactivity reached a steady-state by 10 min. Mean values of k* were the same whether calculated by a single-time point method at 20 min after injection began, or by least-squares fitting of an equation for total brain radioactivity to data at all time points. k* equalled 1.1-1.2 x 10(-4) ml x s(-1) x g(-1) in gray matter and was unaffected by a 2.6-fold increase in CBF caused by hypercapnia. These results indicate that brain incorporation of [1-11C]arachidonate can be quantified in the primate using PET, and that incorporation is flow-independent.
Chang
M C
MC
Laboratory of Neurosciences, National Institute on Aging, National Institutes of Health, Bethesda, MD 20892, USA.
Arai
T
T
Freed
L M
LM
Wakabayashi
S
S
Channing
M A
MA
Dunn
B B
BB
Der
M G
MG
Bell
J M
JM
Sasaki
T
T
Herscovitch
P
P
Eckelman
W C
WC
Rapoport
S I
SI
D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism*; D001921:Brain / Q000000981:diagnostic imaging / Q000378:metabolism*; D002250:Carbon Radioisotopes; D002560:Cerebrovascular Circulation / Q000502:physiology*; D005260:Female; D006935:Hypercapnia / Q000378:metabolism*; D016018:Least-Squares Analysis; D008253:Macaca mulatta; D008297:Male; D010743:Phospholipids / Q000378:metabolism*; D011869:Radioligand Assay; D012016:Reference Values; D014055:Tomography, Emission-Computed
D002250:Carbon Radioisotopes; D010743:Phospholipids; D016718:Arachidonic Acid