ABSTRACT
A permeability barrier between the blood and the brain was first recognized more than a century ago. During the 1970s, much research focused on the passive permeability properties of the blood-brain barrier (BBB) and the way that permeability was altered in various disease states. Experimental studies demonstrated that the ability of a solute to cross the BBB was related to its lipid solubility, and that the increase in the BBB permeability that occurs after injury could be explained by a variety of mechanisms, including loss of endothelial integrity, opening of tight junctions, or induction of transcellular vesicular transport.
