Activity‐Dependent Regulation of Na+,K+‐ATPase α Isoform mRNA Expression In Vivo

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Abstract
To investigate the functional role of the different Na + ,K + -ATPase a (catalytic) subunit isoforms in neuronal cells, we used quantitative in situ hybridization with riboprobes specific for Αl, Α2, and Α3 isoforms to measure the level of a isoform-specific expression in the neuroendocrine cells of the supraoptic (SON) and paraventricular (PVN) nuclei of rat hypothalamus. A prolonged increase in electrical activity of these cells, achieved by 5 days of salt treatment, increased the amount of Α isoform mRNA in the SON and PVN by 50%. Levels of Α mRNA in other brain regions and levels of Α2 and Α3 mRNAs were not affected by salt treatment. We conclude that the Α1 isoform Na + ,K + -ATPase may be specifically adapted to pump out Na + , which enters the cells through voltage-gated channels during neuronal depolarization