ORIGINAL RESEARCH Blood–brain barrier P-glyc

Full list of author information is available at the end of the articleBackground P-glycoprotein (Pgp) is a 170 kDa membrane-bound efflux transporter located in several organs throughout the body with an excretory and/or barrier function, such as the liver, kidneys, intestine, placenta, testes and the blood–brain barrier (BBB) [1]. At the BBB, Pgp is highly expressed and has an important function in the transport of a wide variety of endogenous and exogenous substances out of the brain into the blood-stream [2]. Pgp has been shown to play a role in amyloid-beta clearance from the brain and, as such, has been hypothesized to be involved in the pathogenesis of Alzheimer's disease (AD) [3]. Recently, BBB Pgp dys-function in AD patients was shown using the Pgp sub-strate tracer (R)-[11C]verapamil and positron emission tomography (PET) [4]. Pgp is encoded in the ABCB1 gene (formerly know