Dopamine inhibits the Na-K ATPase activity of the stria vascularis in the cochlea. In vivo ultracytochemical study.

It is believed that the function of the stria vascularis in the cochlea is to produce endolymph. However, the mechanisms that maintain and control the function of the stria vascularis remain unclear. In the present study, to clarify the role of humoral substances in the stria vascularis, a cerium-based method was used to investigate the ultracytochemical effects of intraperitoneal dopamine administration on ouabain-sensitive, K(+)-dependent, p-nitrophenylphosphatase (K-NPPase) activity, which is the second step in the formation of the Na-K ATPase complex, in the stria vascularis of guinea pigs. Na-K ATPase activity was shown to be completely inhibited after dopamine administration. This observation suggests that dopamine inhibits Na-K ATPase activity in the marginal cells of the stria vascularis, and that the stria vascularis may have dopamine receptors. Catecholamines may play an important role in the maintenance and/or control of stria vascularis function.