Cytochemical localization of Na-K ATPase in the guinea pig endolymphatic sac.

The light microscopical and ultracytochemical localization of Na-K ATPase (ouabain-sensitive, potassium-dependent p-nitrophenylphosphatase) in the guinea pig endolymphatic sac was studied by a newly developed lead citrate one step method. The cytochemical reaction product was detected in the epithelial cell layer of the endolymphatic sac at the light microscopical level. At the electron microscopical level, the reaction product was located to the basolateral plasma membrane of both the dark and the light cells. The results suggest that Na-K ATPase may play a role in the ion transport mechanism in the endolymphatic sac.