Effect of norepinephrine on ouabain-sensitive, K+-dependent p-nitrophenylphosphatase activity in strial marginal cells of the cochlea in normal and reserpinized guinea pigs

On the basolateral infoldings of the strial marginal cells in the cochlea, Na-K ATPase activity is abundant. To clarify the humoral control by norepin ephrine, K-NPPase activity of strial marginal cells in the cochlea was inve stigated in normal, reserpine, norepinephrine (NE), reserpine plus NE-treat ed guinea pigs using a cerium-based method. K-NPPase activity was almost co mpletely decreased 3-20 days after reserpine administration. At 10 days aft er reserpinization and following NE repeated treatment, enzyme activity was detectable. These results suggested that norepinephrine might restore and regulate strial K-NPPase activity.