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

Tissue sections and antibodies selectively recognizing isoforms of the α subunit of the Na⁺/K⁺ pump were used to determine the expression of α₁, α₂ and α₃ 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 α₂ isoform of the Na⁺/K⁺ pump. The α₁ 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 α₃ 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 α₃ positive DRG neurons about 75% coexpressed the α₁ isoform of the Na⁺/K⁺ pump. These data show that the expression of the protein of the α subunit isoforms of the Na⁺/K⁺ pump is not uniform throughout the population of DRG neurons and that α₁ is the predominant isoform in the plasma membrane of these neurons.