Manganese (Mn) transport across the rat blood-brain barrier: saturable and transferrin-dependent transport mechanisms.
Using a single capillary pass technique, the transport of manganese (Mn) across the rat blood-brain barrier (BBB) was characterized. Initial rate measurements (15 s) of Mn2+ [0-1000 microM] accumulation in rat brains clearly indicated saturation kinetics by both 1/v vs. 1/s plots, and plots of v vs. [s]. Common carotid injection of freshly mixed Mn2+ with transferrin at a 1:10 molar ratio did not result in a significant change in the initial rate of Mn brain levels compared with injection of Mn2+ alone. However, when Mn2+ was incubated at 25 degrees C in the presence of transferrin at a 1:10 ratio for up to 5 days prior to common carotid injection, the initial rate of Mn uptake by brain was incubation-time-dependent, increasing linearly with prolonged incubations. These findings suggest that the saturable component of divalent Mn transport into brain represents but one of the transport mechanisms for Mn across the BBB. A second transport system for Mn may occur by a transferrin-conjugated Mn transport system.
Aschner
M
M
Department of Pharmacology and Toxicology, Albany Medical College, NY 12208.
Gannon
M
M
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D001812:Blood-Brain Barrier; D017536:Carotid Artery, Common; D007269:Injections, Intra-Arterial; D008297:Male; D008345:Manganese / Q000493:pharmacokinetics*; D051381:Rats; D011919:Rats, Inbred Strains; D013395:Sucrose / Q000493:pharmacokinetics; D014168:Transferrin / Q000494:pharmacology*
D014168:Transferrin; D008345:Manganese; D013395:Sucrose