Non-uniform expression of alpha subunit isoforms of the Na+/K+ pump in rat dorsal root ganglia neurons

Tissue sections and antibodies selectively recognizing isoforms of the alpha subunit of the Na+/K+ pump were used to determine the expression of alpha1, alpha2 and alpha3 pump isoforms in the plasma membrane of adult rat dorsal root ganglia (DRG) neurons. There was no detectable membrane signal from DRG neurons that were probed with antibodies to the alpha2 isoform of the Na+/K+ pump. The alpha1 isoform of the Na+/K+ pump was found in most (77+/-4%) studied DRG neurons, regardless of cell size. Only 16+/-7% of the neurons expressed a detectable level of the alpha3 Na+/K+ pump and all were apparently from a subpopulation of large DRG neurons. Comparison of cell size distributions and a study of neurons identified in serial sections suggested that of the alpha3 positive DRG neurons about 75% coexpressed the alpha1 isoform of the Na+/K+ pump. These data show that the expression of the protein of the alpha subunit isoforms of the Na+/K+ pump is not uniform throughout the population of DRG neurons and that alpha1 is the predominant isoform in the plasma membrane of these neurons.