Blood-brain barrier amino acid permeability

Tang, J. P., Xu, Z. Q., Douglas, F. L., Rakhit, A., and Melethil, S. Increased blood-brain barrier permeability of amino acids in chronic hypertension, Life Sci., 53, L417, 1993. 

All these models describe small data sets with only limited predictability for other series of compounds. With the increasing importance of combinatorial chemistry and high-throughput screening, it became necessary to formulate more general models for oral bioavailability and blood-brain barrier permeability. Such quantitative models for oral bioavailability are difficult to derive there is a lack of consistent data and many drugs are either absorbed by an active transport (e.g., by the amino acid or dipeptide transporters), or are eliminated by one of several different efflux pumps. 

This correlation is useful for rapid estimation of the blood-brain barrier permeability. More accurate estimation can be obtained by examining other physical characteristics of the compound, such as cross-sectional area and critical micelle concentration [27] (Figure 5.28). Because of the extremely low permeability of brain capillaries to most molecules, brain endothelial cells have a variety of specialized transport systems—including transporters for glucose, amino acids, insulin, and transferrin—that enable essential molecules to move from the blood into the brain extracellular space. Useful reviews of the blood-brain barrier are available [28, 29]. 

Kerper LE, Ballatori N, Clarkson TW (1992) Methylmercury transport across the blood-brain barrier by an amino acid carrier. Am J Physiol 262 R761-R765 Kinter WB, Pritchard JB (1977) Altered permeability of cell membranes. In DHK See (ed) Handbook of physiology—reactions to environmental agents. American Physiol Society, Baltimore, MD, pp 563-576 Knauf PA, Rothstein A (1971) Effects of sulfhydryl and amino reactive reagents on anion and cation permeability of the human red blood cell. J Gen Physiol 58 190-210... 

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