Tissue distribution of mRNAs encoding the alpha isoforms and beta subunit of rat Na+,K+-ATPase.

The tissue distribution of the multiple forms of rat Na+,K+-ATPase was examined at the molecular level with cDNA probes specific for the alpha, alpha (+), alpha III and beta subunit mRNAs. Northern and slot blot analyses demonstrate that these mRNAs are produced in a tissue-specific manner. RNAs encoding the alpha (+) isoform are detected in kidney, brain, heart, adipose, muscle, stomach and lung, whereas alpha III RNA is detected in brain, stomach and lung. Both alpha and beta mRNAs are present in all the tissues studied, although at very different levels. Examination of heart tissue in greater detail demonstrates that the levels of mRNA encoding the alpha subunit are greater in the atria than in the ventricles, while the converse is true for alpha (+).