ArticleMolecular pharmaceutics2013
Factors that limit positron emission tomography imaging of p-glycoprotein density at the blood-brain barrier.
Article in Molecular pharmaceutics, 2013. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 6 papers.
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Who cites it
6 citing papers in PubMed, 21 citations in OpenAlex.
- Imaging the Activity of Efflux Transporters at the Blood-Brain Barrier in Neurologic Diseases: Radiotracer Selection Criteria.Journal of nuclear medicine : official publication, Society of Nuclear Medicine · 2025Review
- Synthesis and preliminary preclinical evaluation of fluorine-18 labelled isatin-4-(4-methoxyphenyl)-3-thiosemicarbazone ([EJNMMI radiopharmacy and chemistry · 2018Article
- Influence of breast cancer resistance protein and P-glycoprotein on tissue distribution and excretion of Ko143 assessed with PET imaging in mice.European journal of pharmaceutical sciences : official journal of the European Federation for Pharmaceutical Sciences · 2018Article
- (18)F-FCWAY, a serotonin 1A receptor radioligand, is a substrate for efflux transport at the human blood-brain barrier.NeuroImage · 2016Article
- Tariquidar Is an Inhibitor and Not a Substrate of Human and Mouse P-glycoprotein.Drug metabolism and disposition: the biological fate of chemicals · 2016Article
- The Inhibitor Ko143 Is Not Specific for ABCG2.The Journal of pharmacology and experimental therapeutics · 2015Article
Corrections and comments
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Authors and funding
7 authors at 5 institutions in 3 countries.
Funding
Abstract
Efflux transporters located at the blood-brain barrier, such as P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP), regulate the passage of many drugs in and out of the brain. Changes in the function and density of these proteins, in particular P-gp, may play a role in several neurological disorders. Several radioligands have been developed for measuring P-gp function at the blood-brain barrier of human subjects with positron emission tomography (PET). However, attempts to measure P-gp density with radiolabeled inhibitors that bind to these proteins in vivo have not thus far provided useful, quantifiable PET signals. Herein, we argue that not only the low density of transporters in the brain as a whole but also their very high density in brain capillaries act to lower the concentration of ligand in the plasma and thereby contribute to absent or low signals in PET studies of P-gp density. Our calculations, based on published data and theoretical approximations, estimate that whole brain densities of many efflux transporters at the blood-brain barrier range from 0.04 to 5.19 nM. We conclude that the moderate affinities (>5 nM) of currently labeled inhibitors may not allow measurement of efflux transporter density at the blood-brain barrier, and inhibitors with substantially higher affinity will be needed for density imaging of P-gp and other blood-brain barrier transporters.
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Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.