Effects of centrophenoxine on the monovalent electrolyte contents of the large brain cortical cells of old rats.

The effect of centrophenixine has been studied on the monovalent electrolyte contents of the brain cortical cells of old female Wistar rats by means of energy dispersive x-ray microanalysis. The drug was administered in form of an intraperitoneal injection of 100 mg/kg body weight for 20 days. The treatment decreased the potassium content in both the nucleus and cytoplasm in terms of dry mass fraction, whereas the sodium concentration remained unchanged. The Na+/K+ ration increased significantly in both cell compartments. The chloride content of the nuclei decreased slightly. If one supposes just 1--2% rehydration of the old cytoplasm, the decrease of the total ionic strength may be of considerable extent, it may even reach the values obtained in young adult animals. The results are interpreted in terms of a recently developed 'membrane hypothesis' of aging.