M. Aschner et M. Gannon, MANGANESE (MN) TRANSPORT ACROSS THE RAT-BLOOD BRAIN BARRIER - SATURABLE AND TRANSFERRIN-DEPENDENT TRANSPORT MECHANISMS, Brain research bulletin, 33(3), 1994, pp. 345-349
Using a single capillary pass technique, the transport of manganese (M
n) across the rat blood-brain barrier (BBB) was characterized. Initial
rate measurements (15 s) of Mn2+ [0-1000 muM] accumulation in rat bra
ins clearly indicated saturation kinetics by both 1/v vs. 1/s plots, a
nd plots of v vs. [s]. Common carotid injection of freshly mixed Mn2with 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 th
e presence of transferrin at a 1:10 ratio for up to 5 days prior to co
mmon carotid injection, the initial rate of Mn uptake by brain was inc
ubation-time-dependent, increasing linearly with prolonged incubations
. These findings suggest that the saturable component of divalent Mn t
ransport into brain represents but one of the transport mechanisms for
Mn across the BBB. A second transport system for Mn may occur by a tr
ansferrin-conjugated Mn transport system.