AJP - Regulatory, Integrative and Comparative Physiology, Vol 261, Issue 2 478-R483, Copyright © 1991 by American Physiological Society
Regional blood-brain barrier transport of cationized bovine serum albumin in awake rats
M. Shimon-Hophy, K. C. Wadhwani, K. Chandrasekaran, D. Larson, Q. R. Smith and S. I. Rapoport
Laboratory of Neurosciences, National Institute on Aging, National Institutes of Health, Bethesda, Maryland 20892.
Regional blood-brain barrier permeability-surface area products (PAs) of
cationized bovine serum albumin (cBSA) with isoelectric point (pI)
approximately 8 or greater than or equal to 11 and of native bovine serum
albumin (nBSA;pI approximately 4) were determined in awake male
Sprague-Dawley rats after bolus intravenous injection. The albumins were
labeled with 125I. Brain uptakes were assessed by autoradiography and by
direct assay of radioactivity in brain regions. nBSA uptake into brain was
statistically insignificant over 3 h, whereas cBSA uptake was significantly
even at 6 min. Mean PA values of cBSA with pI approximately 11 (1.69-2.65 x
10(-5) ml.s-1.g-1) in most brain regions were twofold higher than PAs of
cBSA with pI approximately 8 (0.98-1.37 x 10(-5) ml.s-1.g-1), whereas mean
PA for nBSA did not differ significantly from zero. Autoradiographs of
brain slices and net distributions in brain compartments at 6 and 30 min
after injection suggested that cBSA entered the brain parenchyma via blood
vessels and cerebrospinal fluid but that the former was the main route. The
results quantitate for the first time regional brain PA values for
cationized proteins and suggest specific mechanisms at cerebral blood
vessels that distinguish transport of cationized from noncationized
macromolecules.
