Distribution of immunoreactive α- and β-subunit isoforms of Na,K-ATPase in the gerbil inner ear

Abstract

Biochemical and histochemical studies have demonstrated abundant Na,K- ATPase in the inner ear and provided new information concerning the ion transport capacities of specialized cell types. To extend these earlier observations, we immunostained inner ears from adult gerbils with antibodies specific for the three known α- and the two known β isoforms of Na,K- ATPase. Different inner ear cell types contained specific and distinct combinations of α- and β-subunit isoforms. Strial marginal cells and vestibular dark cells expressed the α1- and β2-isoforms, whereas other positive epithelial cells expressed α1 in combination with β1. Ganglion neurons and their peripheral processes showed positive immunostaining for the α3- and β1-subunit isoforms. Subpopulations of fibrocytes in the spiral prominence, suprastrial and supralimbal regions, and vestibular system expressed either the α1- or α2-isoform, or both. The differential expression of Na,K-ATPase subunit isoforms presumably reflects different K+ and Na+ transport capacities among inner ear cell types which, working in concert, serve to generate and maintain the unique ionic and electrical environment in the mammalian inner ear.