Transport of [125I]transferrin through the rat blood-brain barrier

Brain Res. 1995 Jun 19;683(2):164-71. doi: 10.1016/0006-8993(95)00363-u.


Transferrin receptors are present in the plasma membrane of brain endothelial cells but it is unclear if these receptors mediate transport of transferrin across the blood-brain barrier (BBB). In the present study, the transport of rat holo-transferrin (rTf) across the BBB in vivo was evaluated in ketamine anesthetized rats (250-300 g) both by in situ brain perfusion coupled with capillary depletion analysis and by thaw-mount autoradiography. [125I]rTf was infused through the right internal carotid artery at a rate of 3.65 ml/min for 2.5-5 min. After a 5 min perfusion, the volume of distribution (VD) of [125I]rTf in the brain homogenate, the postvascular supernatant, or the vascular pellet was 55.8 +/- 4.5, 43.5 +/- 4.8, and 8.7 +/- 2.3 microliters/g, respectively. Co-infusion of [125I]rTf with unlabeled rTf or with a high dose of OX26 monoclonal antibody to the rat transferrin receptor significantly reduced the [125I]rTf transport, and in the presence of 10% rat serum [125I]rTf transport was nearly entirely abolished. The transport of [125I]rTf across the BBB in vivo was demonstrated by thaw-mount autoradiography, which showed silver grains well within brain parenchyma following a 5 min internal carotid artery perfusion. These studies are consistent with the following conclusions: (a) in the absence of competing plasma transferrin, [125I]holo-transferrin is transported through the BBB at a rate comparable to the OX26 monoclonal antibody; and (b) the ability to detect measurable transport of perfused [125I]transferrin is greatly inhibited by a small contamination of the perfusate by rat serum, which contains high concentrations of competing transferrin.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Antibodies, Monoclonal
  • Autoradiography
  • Biological Transport / immunology
  • Biological Transport / physiology
  • Blood Proteins / pharmacology
  • Blood-Brain Barrier / immunology
  • Blood-Brain Barrier / physiology*
  • Capillaries / metabolism
  • Carotid Arteries / metabolism
  • Iodine Radioisotopes
  • Male
  • Perfusion
  • Rats
  • Rats, Sprague-Dawley
  • Regional Blood Flow
  • Transferrin / pharmacokinetics*
  • Tritium


  • Antibodies, Monoclonal
  • Blood Proteins
  • Iodine Radioisotopes
  • Transferrin
  • Tritium