The Role of L-threo DOPS in the Control of Na-K ATPase Activity of the Marginal Cells in the Stria Vascularis of Reserpinized Guinea Pigs

Abstract

It is believed that the function of the stria vascularis in the cochlea is to produce endolymph. The mechanisms that maintain or control the function of the stria vascularis, however, remain unclear. In a previous study, we investigated the ultracytochemical effects of one-shot reserpine administration on the Na-K ATPase activity of the stria vascularis in guinea pigs. Na-K ATPase activity was shown to be completely inhibited 3-20 days after reserpinization, whereas in the present study at 20 days after reserpinization and following L-threo DOPS treatment, Na-K ATPase activity was detectable. As reserpine is an adrenergic neuron blocker, and L-threo DOPS is the precursor of noradrenaline, it seems that noradrenaline converted from L-threo DOPS was able to restore the Na-K ATPase activity in the reserpinized animals. These results suggest that catecholamines may play an essential role in the maintenance or control of the Na-K ATPase activity, and that the stria vascularis may be one of the target organs of catecholamines.

Key Words:

• L-threo-3,4-dihydroxyphenylserine (L-threo DOPS)
• noradrenaline
• catecholamine
• K-NPPase activity
• ultracytochemical study