(Na+ −K+) dependent ATPase in mouse submaxillary gland

Abstract

The influences of castration and of testosterone administration on (NaK)-ATPase in mouse submaxillary gland has been studied. Electron microscopical and histochemical data showing a profound change in the structure of the granular tubules after castration are also presented. Whereas testosterone administration is followed by a proliferation of the rough and smooth endoplasmic reticulum in the cells of the granular tubules, castration results in an opposite change. After castration, alkaline phosphatase, which is primarily localized in the basal membranes of the granular tubules, is drastically reduced. The tissue was fractionated, by the procedure of Katz and Epstein [15], and microsomal membranes were isolated by a modification of the procedure described by Schwartzet al. [29]. Plasma membranes were isolated by the method of Henninget al. [9]. As regards MgNaK-ATPase activity in plasma membranes, castration produced a slight decrease inV max values. In the same membrane preparation, a completely opposite results was obtained for NaK-ATPase. In microsomal membranes a tremendous increase inV max with a change inK m occured when potassium chloride was varied. When sodium chloride was constant and KCl concentration varied, the same high increase inV max was recorded, but inK m the decrease was not so strongly pronounced. The conclusion was reached that the high specific activity of NaK-ATPase in castrated mouse submaxillary gland may be a consequence of a different amount of membrane protein per unit of tissue weight.