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 AlCl_{3} 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 > AlCl_{3}. 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.
Institute of Virology, Vaccines and Sera Torlak, Vojvode Stepe 458, 11221 Belgrade, Serbia. ericjovicic@sbb.co.yu
Milena Erić
ME
Jovicić
Miroljub
M
Popović
Katica Jovanova
KJ
Nesić
Natalija
N
Popović
Svetlana Jovicić
SJ
Pavlović
Ljubisav
L
Rakić
D000255:Adenosine Triphosphate / Q000097:blood; D000367:Age Factors; D000077410:Aluminum Chloride; D017607:Aluminum Compounds / Q000633:toxicity*; D000544:Alzheimer Disease / Q000201:enzymology*; D000818:Animals; D020532:Basal Nucleus of Meynert / Q000187:drug effects* / Q000201:enzymology; D002712:Chlorides / Q000633:toxicity*; D002799:Cholinergic Fibers / Q000502:physiology; D004195:Disease Models, Animal; D004910:Erythrocyte Membrane / Q000201:enzymology*; D007276:Injections, Intraventricular; D007608:Kainic Acid / Q000633:toxicity*; D008297:Male; D011188:Potassium / Q000097:blood; D051381:Rats; D017208:Rats, Wistar; D012964:Sodium / Q000097:blood; D000254:Sodium-Potassium-Exchanging ATPase / Q000097:blood*; D013379:Substrate Specificity
D017607:Aluminum Compounds; D002712:Chlorides; D000077410:Aluminum Chloride; D000255:Adenosine Triphosphate; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium; D007608:Kainic Acid