Localization of ATPase activity to the glial-like cells of the pars intermedia.

Abstract

Abstract An adenosine triphosphatase was histochemically localized in the pars intermedia of the pituitary of the frog, Rana berlandieri forrei . The reaction product was found primarily between membranes of stellate (glial-like) cells and secretory cells and could be partially inhibited by ouabain. It was also present between two stellate cell membranes and in other intermembrane spaces bounded on at least one side by a stellate cell. In no instance was reaction product seen between membranes of two secretory cells or on the surface of stellate cells not contacted by other cellular elements. Thus, it is suggested that stellate cells contain an ATPase, possibly a Na + K + -activated ATPase, which might then allow these cells to serve as regulators of the extracellular ionic environment. Furthermore, since ouabain or removal of K + is inhibitory to melanophore-stimulating hormone (MSH) secretion from isolated pars intermedia in vitro , it is also possible that these cells may play a functional role in the control of MSH secretion.