Age-related alterations by chronic intermittent hypoxia on cerebral synaptosomal ATPase activities.
The age-related alterations in the plasticity of synaptic energy-requiring ATPases [Na+,K(+)-ATPase, low- and high-affinity Ca(2+)-ATPase, Mg(2+)-ATPase, and Ca2+,Mg(2+)-ATPase] were assayed in synaptosomes and synaptosomal subfractions [namely, synaptosomal plasma membranes and synaptic vesicles] in the cerebral cortex from 3- and 24-month-old normoxic rats and rats subjected to either mild or severe chronic (four weeks) intermittent normobaric hypoxia. With the exception of the high-affinity Ca(2+)-ATPase, aging induced a decrease in the ATPase activities from normoxic rats. The adaptation to mild hypoxia was characterized by an increase in the activity of Mg(2+)-ATPase in 3-month-old rats, concomitant with a decrease in the activities of: (i) Na+,K(+)-ATPase and high-affinity Ca(2+)-ATPase in both 3- and 24-month-old rats, and (ii) Ca2+,Mg(2+)-ATPase in 3-month-old ones. The adaptation to chronic intermittent severe hypoxia was characterized by a decrease in the activities of: (i) Na+,K(+)-ATPase, Ca2+,Mg(2+)-ATPase and high-affinity Ca(2+)-ATPase in both 3- and 24-month-old rats, and (ii) low-affinity Ca(2+)-ATPase only in 24-month-old ones. The effect on Mg(2+)-ATPase activity was characterized by a decrease in the activity of the enzymatic form located in the synaptic plasma membranes [involved in ATP hydrolysis to adenosine production], concomitant with an increase in the activity of the form located in the synaptic vesicles [involved in the turnover of transmitters, e.g., glutamate].
Benzi
G
G
Institute of Pharmacology, State University of Pavia, Italy.
Gorini
A
A
Arnaboldi
R
R
Ghigini
B
B
Villa
R F
RF
D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000375:Aging / Q000378:metabolism*; D000704:Analysis of Variance; D000818:Animals; D017301:Ca(2+) Mg(2+)-ATPase / Q000378:metabolism; D000252:Calcium-Transporting ATPases / Q000378:metabolism; D002540:Cerebral Cortex / Q000201:enzymology* / Q000254:growth & development; D002908:Chronic Disease; D002534:Hypoxia, Brain / Q000201:enzymology*; D051381:Rats; D012016:Reference Values; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism; D013572:Synaptic Vesicles / Q000201:enzymology; D013574:Synaptosomes / Q000201:enzymology*
D000251:Adenosine Triphosphatases; D017301:Ca(2+) Mg(2+)-ATPase; D000252:Calcium-Transporting ATPases; D000254:Sodium-Potassium-Exchanging ATPase