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This report is a summary of the presentations of a symposium sponsored by the American Society for Pharmacology and Toxicology (ASPET) held April 26-30 at Experimental Biology 2014 in San Diego, CA. The presentations focused on the role of transporters in imaging in health and disease and on assessing transporter function in vivo. Imaging is an import diagnostic tool in clinics and is a novel tool to visualize in vivo the function of transporters. Many imaging substrates and endogenous markers for organ function are organic anions. In this symposium, the bile salt transporter sodium taurocholate cotransporting polypeptide (NTCP) and the liver organic anion transporting polypeptides (OATPs) as well as the renal organic anion transporters (OATs) were addressed in detail. E.g., OATPs mediate transport of contrast agents used for magnetic resonance imaging of the liver or transport agents used for hepatobiliary scintigraphy, while OATs transport substances used in renography. In addition, the multidrug resistance transporter 1 (MDR1 or P-gp), which is the most important gate keeper in epithelial or endothelial barriers for preventing the entry of potentially harmful substances into organs was addressed. Novel substrates suitable for positron emission tomography (PET) allow studying such transporters at the blood brain barrier or while mediating uptake of drugs into hepatocytes and, importantly, PET tracers allow now also renography. Finally, quantitative data on transporter expression in human organs allow the development of improved physiologically based pharmacokinetic (PBPK) models for drug disposition. Hence, the combined effort using novel substrates for in vivo visualization of transporters and quantification of transporters will lead to a deeper understanding of transporter function in disease and allow development of novel PBPK models for disease states. This article has not been copyedited and formatted. The final version may differ from this version. DMD Fast Forward. Published on September 23, 2014 as DOI: 10.1124/dmd.114.059873 at A PE T Jornals on M ay 8, 2017 dm d.aspurnals.org D ow nladed from