Cation Transport and Cochlear Function

Abstract

Na-K-activated ATPase was determined in the cochlear structures by ultramicro-analytical methods. The highest activity was found in the stria vascularis, with a decrease from base to apex. Ouabain, which inhibits the isolated enzyme system, appeared to diminish the CMP and + EP to the same extent. These findings strongly suggest that the Na-K— ATPase enzyme system in the stria vascularis plays the key role in the maintenance of the cochlear cationic gradients, while such a role appears highly unlikely for Reissner's membrane. The CMP and +EP appear to depend on the functioning of this pump system.