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

Tissue sections and antibodies selectively recognizing isoforms of the alph a subunit of the Na+/K+ pump were used to determine the expression of alpha (1), alpha(2) and alpha(3) pump isoforms in the plasma membrane of adult ra t dorsal root ganglia (DRG) neurons. There was no detectable membrane signa l from DRG neurons that were probed with antibodies to the alpha(2) isoform of the Na+/K+ pump. The alpha(1) isoform of the Na+/K+ pump was found in m ost (77 +/- 4%) studied DRG neurons, regardless of cell size. Only 16 +/- 7 % of the neurons expressed a detectable level of the alpha(3) Na+/K+ pump a nd all were apparently from a subpopulation of large DRG neurons. Compariso n of cell size distributions and a study of neurons identified in serial se ctions suggested that of the alpha(3) positive DRG neurons about 75% coexpr essed the alpha(1) isoform of the Na+/K+ pump. These data show that the exp ression of the protein of the alpha subunit isoforms of the Na+/K+ pump is not uniform throughout the population of DRG neurons and that alpha(1) is t he predominant isoform in the plasma membrane of these neurons. (C) 1999 El sevier Science B.V. All rights reserved.