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Charge effects of the blood‐brain barrier on the transport of charged molecules
Author(s) -
Fu Bingmei M,
Li Guanglei,
Yuan Wei
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.734.1
Subject(s) - glycocalyx , charge density , surface charge , chemistry , biophysics , electric charge , charge (physics) , basement membrane , molecule , chemical physics , biochemistry , physics , biology , anatomy , organic chemistry , quantum mechanics
The endothelial surface glycocalyx layer and the basement membrane (BM) are two important components of the blood‐brain barrier (BBB). They provide large resistance to solute transport across the BBB in addition to the tight junctions in the cleft between endothelial cells. Due to their glycosaminoglycan compositions, they are believed to carry negative charge. To quantify their charge effects, we used quantitative fluorescence imaging microscopy to measure the permeability (P) of the BBB to two similar sized globular proteins, ribonuclease (net charge=+3) and α‐lactalbumin (net charge=−11). The mean P ribonuclease was 6.2 × 10 −7 cm/s (n=11), which is ~4 times of P α‐lactalbumin . To determine the charge densities in the glycocalyx layer and in the BM, we developed a mathematical model for the transport of charged molecules across the BBB. In this model, constant charge densities are assumed in the surface glycocalyx layer and in the BM. At their interfaces with non‐charge regions of the BBB, the electrostatic and steric exclusions to charged molecules are considered. Our model predicts that to account for the 4‐folds difference in measured P ribonuclease and P α‐lactalbumin , the charge density in both the surface glycocalyx and the BM would be ~25 meq/l. This work is supported in part by the Andrew Grove Foundation and NSF.