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Abstract #1991

Does Li Displace Intracellular Na in Brain?: An In Vivo 23Na MRI Study

Richard A. Komoroski1, Diana M. Lindquist2, John M. Pearce2

1Center for Imaging Research, University of Cincinnati, Cincinnati, OH, United States; 2Imaging Research Center, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States

Elevated intracellular Na, possibly arising from abnormal Na,K-ATPase, has been proposed in bipolar disorder. Lithium is often an effective treatment for bipolar disorder. Sodium-23 MRI was used to follow the effect of an IP dose of Li on intracellular Na in normal rat brain in vivo. For brain parenchyma, 23Na MRI intensity increased by a maximum of 6.78% at 1.4 hrs after Li injection and then fell slightly over the next two hours. Sodium-23 T2s generally lengthened with time, consistent with intra- to extracellular movement of Na. The results are interpreted as displacement of intracellular Na by Li.