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

The contributions of individual components of blood to brain [C-14]palmitate uptake and incorporation were studied with the ill situ brain perfusion technique in the pentobarbital-anesthetized rat. With whole-blood perfusate, brain unacylated [C-14]palmitate uptake was linear with time and extrapolated to zero at T = 0 s of perfusion. Tracer accumulated in brain with a blood-to-brain transfer coefficient of 1.8 +/- 0.1 x 10(-1) mL/s/g (whole cerebral hemisphere). Incorporation into brain lipids was rapid such that similar to 40% of tracer in brain at 45 s of perfusion was in cerebral phospholipids and neutral lipids. Similar rates of uptake were obtained during unacylated [C-14]palmitate perfusion in whole rat plasma, serum, or artificial saline containing 2-3 % albumin, suggesting that albumin has a key role in determining [C-14]palmitate uptake in brain. The excellent match in brain uptake rates between whole blood and albumin-containing saline fluid suggests that the perfusion technique will be useful method for quantifying the individual contributions of blood constituents and albumin binding on brain [C-14]palmitate uptake.