Baran, A.M., T.M. Spranger, A.E. Moseley, J.B. Lingrel, and M.L. Caspers
The (Na+, K+)-ATPase maintains Na+ and K+ gradients in cells through the active transport of these ions across the plasma membrane. [3H]Ouabain, which binds with high affinity to the α-2 and α-3 isoforms of the (Na++K+)-ATPase, was used to study the distribution of these isoforms in the brains of adult wild type and heterozygous α-2 knockout mice of FVBN genetic background. Frozen, coronal brain sections (24 micron) were prepared and were assayed in a 100 mM Tris-HCl buffer containing 10 mM NaCl, 10 mM MgCl2, 5 mM ATP and 29 nM [3H]ouabain. The sections were exposed to Kodak BioMax Scientific Imaging film and the images were subjected to computer-assisted densitometry. In α-2 heterozygotes, significant decreases in the relative density of [3H]ouabain binding sites were observed in the cerebral cortex (5.1%) and hippocampus (4.4%) compared to wild-type mice. These findings are similar to results obtained with C57BL6 mice where small decreases in [3H]ouabain binding sites were observed in the cerebral cortex, hippocampus and thalamus of heterozygous α-2 knockout mice but are dissimilar to results using α-2 heterozygous 129/Black Swiss (mixed) mice where larger decreases in [3H]ouabain binding, relative to wild-type animals, were seen in all brain regions tested (Program #517.10, 2004 Abstract Viewer/Itinerary Planner, Washington, DC: Society for Neuroscience, CD-ROM). Strain differences also are seen in the survival time of homozygous α-2 knockout mice; FVBN knockout mice live approximately 1 day whereas the mixed and C57BL6 knockout mice die at birth. (Supported by NIH grants HL28573 and HL66062 and a gift from J.D. Rose.)
Presented at the 2005 Society for Neuroscience meeting, Washington, D.C. and 2007 spring American Chemical Society meeting, Chicago, IL.