UPTAKE OF GA-67 INTO RAT CEREBRAL HEMISPHERE AND CEREBELLUM - COMPARISON WITH FE-59

Transferrin and transferrin receptors play an important role in the tr ansport of iron into the brain, To determine whether gallium enters th e brain by the same mechanism, uptakes of Ga-67 and Fe-59 have been co mpared under controlled conditions, Rates of gallium penetration into brain (K-in) were four times slower than those for Fe-59, K-in for Ga- 67 when infused with citrate were 0.88+/-0.24 and 0.94+/-0.39x10(-3) m l g(-1)h(-1) for cerebral hemisphere and cerebellum, respectively, Whe n infused as the transferrin complex, Ga-67 uptake into the brain was not different from that when infused with citrate, The presence of the anti-transferrin receptor antibody OX-26 significantly reduced uptake of Fe-59 by 60% and 64% into cerebral hemisphere and cerebellum, resp ectively., By contrast, pretreatment of rats with OX-26 enhanced the u ptake of Ga-67 into brain, particularly when infused with citrate; mea n increases in uptake of Ga-67 were 120% and 144% for cerebral hemisph ere and cerebellum, respectively, Purified Ga-67-transferrin was also taken up into both brain regions examined in the presence of OX-26, Th ese results indicate that the transport of non-transferrin bound galli um is an important mechanism for gallium uptake into brain.