Aging, aluminium and basal forebrain lesions modify substrate kinetics of erythrocyte membrane Na,K-ATPase in the rat.

Several studies suggested that the activity of erythrocyte Na,K-ATPase declines with aging. Here, it is postulated that alterations in the substrate kinetics of the erythrocyte membrane Na,K-ATPase could be more aggravated in conditions of brain cholinergic dysfunction seen in Alzheimer's disease than in normal aging. To test this hypothesis, we compared the Na,K-ATPase activity (Vmax/Km parameters) in aged rats with those in young rats with brain cholinergic dysfunction induced by electrolytic-, kainic acid-lesioned nucleus basalis magnocellularis (NBM) or by intracerebroventricular AlCl3 administration. In the above mentioned groups, Vmax values were significantly lower in comparison to the control animals. Furthermore, Km values were significantly higher in animals with electrolytic-induced NBM lesions, AlCl 3 treated rats and aged animals. However, Km was significantly lower in kainic acid-induced NBM lesions compared to the control group. The Na,K-ATPase catalytic efficiency, estimated by the ratio Vm/Km, decreased as followed: young animals > aged animals > kainic acid lesion > electrolityc lesion > AlCl3. Our data suggest that neurodegenerative processes similar to those seen in Alzheimer's disease affect the sodium/potassium pump functionality which might be detected in peripheral blood erythrocyte membranes.