Enzyme Histochemistry of the Ventricular Choroid Plexus (Part IV)

The Localization of Mg²⁺-ATPase and Na⁺, K⁺-ATPase (p-nitrophenylphosphatase) Activities

Abstract

To determine the ultracytochemical localization of Na⁺, K⁺-ATPase and Mg²⁺-ATPase activities on normal rat choroidal epithelium, the Mayahara et al.'s one-step lead citrate method and Wachstein and Meisel's technique were employed.
The electron dense reaction products which are sensitive to ouabain (10^-3-10^-4M) were observed to be abundant inside the microvilli and to be positively present along the outside of the basal plasmalemmas of the choroidal epithelium. The Mg²⁺-ATPase activity was seen as electron dense reaction along the outside of the choroidal basal plasmalemmas.
Na⁺, K⁺-ATPase activity is thought to be involved in cerebrospinal fluid secretion through the active movement of Na⁺ in the choroidal epithelial cell. The Na⁺-K⁺ exchange pumps are thought to localize both in the plasmalemma of the microvilli and in the basal plasmalemmas of the choroid plexus epithelial cell.