Fatty acid uptake and incorporation in brain - Studies with the perfusion model

The contributions of individual components of blood to brain [C-14]palmitat e uptake and incorporation were studied with the ill situ brain perfusion t echnique in the pentobarbital-anesthetized rat. With whole-blood perfusate, brain unacylated [C-14]palmitate uptake was linear with time and extrapola ted to zero at T = 0 s of perfusion. Tracer accumulated in brain with a blo od-to-brain transfer coefficient of 1.8 +/- 0.1 x 10(-1) mL/s/g (whole cere bral hemisphere). Incorporation into brain lipids was rapid such that simil ar to 40% of tracer in brain at 45 s of perfusion was in cerebral phospholi pids and neutral lipids. Similar rates of uptake were obtained during unacy lated [C-14]palmitate perfusion in whole rat plasma, serum, or artificial s aline containing 2-3 % albumin, suggesting that albumin has a key role in d etermining [C-14]palmitate uptake in brain. The excellent match in brain up take rates between whole blood and albumin-containing saline fluid suggests that the perfusion technique will be useful method for quantifying the ind ividual contributions of blood constituents and albumin binding on brain [C -14]palmitate uptake.