We examined Na+,K+-ATPase activity in four regions of the gerbil cochlear lateral wall by measuring intracellular Na+ concentration ([Na+](i)). The application of 1 mM ouabain and removal of external K+ caused a most striking increase in [Na+l(i) of the suprastrial fibrocytes, followed by the stria vascularis and the type II fibrocytes, but no detectable response in the type I fibrocytes. These results may imply the potency of the Na+,K+-ATPase activity. The high values of the resting [Na+](i) in these cells under perilymph-like solution returned to the [Na+](i) within physiological values after exposure to low-Na+ conditions similar to endolymph. Our results are interpreted in the light of recent morphological findings with regard to the roles in the secretion of K+ into endolymph of several cell types within the lateral wall.
- Cochlear lateral wall
- Intracellular Na concentrations
- Stria vascularis
ASJC Scopus subject areas