An active transport system in the blood-brain barrier may reduce levodopa availability.
Levodopa, the primary drug used to treat patients with Parkinson's disease, is transported into the brain by the facilitative amino acid transporter (L1). We present here an unanticipated discovery: levodopa may be pumped out of the brain by a Na(+)-dependent transport system that couples the naturally occurring Na(+) gradient existing between the brain's extracellular fluid and the cytoplasm of capillary endothelial cells. The activity of this system reduces the net availability of levodopa.
Hawkins
Richard A
RA
Department of Physiology and Biophysics, The Chicago Medical School, Rosalind Franklin University of Medicine and Science, 3333 Green Bay Road, North Chicago, IL 60064, USA. Richard.Hawkins@rosalindfranklin.edu
Mokashi
Ashwini
A
Simpson
Ian A
IA
D000818:Animals; D001693:Biological Transport, Active / Q000502:physiology*; D001812:Blood-Brain Barrier / Q000378:metabolism*; D002199:Capillary Permeability / Q000187:drug effects / Q000502:physiology; D002417:Cattle; D015259:Dopamine Agents / Q000493:pharmacokinetics*; D004305:Dose-Response Relationship, Drug; D042783:Endothelial Cells / Q000187:drug effects; D045604:Extracellular Fluid / Q000187:drug effects; D007532:Isoleucine / Q000378:metabolism; D007980:Levodopa / Q000493:pharmacokinetics*; D008954:Models, Biological; D012964:Sodium / Q000378:metabolism; D013997:Time Factors; D014316:Tritium / Q000493:pharmacokinetics
D015259:Dopamine Agents; D007532:Isoleucine; D014316:Tritium; D007980:Levodopa; D012964:Sodium