Effects of aluminum chloride on the kinetics of rat cortex synaptosomal ATP diphosphohydrolase (EC 3.6.1.5).
Aluminum chloride (AlCl3), a neurotoxic compound, inhibited ATP diphosphohydrolase activity of synaptosomes obtained from cerebral cortex of adult rats. The metal ion significantly inhibited ATPase and ADPase activities of the enzyme at all concentrations tested in vitro (0.01, 0.05, 0.5, 5, and 10 mM) in the presence of 1.5 mM calcium. When tested in the absence of Ca2+, and with increasing amounts of Al3+, enzyme activity remained below basal levels, suggesting that the trivalent cation Al3+ is not a substitute for the divalent cation Ca2+ in ATP-Ca2+ and ADP-Ca2+ complexes. The Al3+ inhibition was competitive with respect to Ca2+. The enzyme inhibition was reversed by the addition of deferoxamine (DFO). NaF significantly inhibited ATP diphosphohydrolase activity, and this inhibition was reversed by the addition of Ca2+ to the medium. Such inhibition was not potentiated by AlF4, which is an inhibitor of cation-transport ATPases.
Schetinger
M R
MR
Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Brasil.
Wyse
A T
AT
Da Silva
L B
LB
Barcellos
C K
CK
Dias
R D
RD
Sarkis
J J
JJ
D000251:Adenosine Triphosphatases / Q000037:antagonists & inhibitors; D000077410:Aluminum Chloride; D017607:Aluminum Compounds / Q000633:toxicity*; D000818:Animals; D001081:Apyrase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D001252:Astringents / Q000633:toxicity*; D002118:Calcium / Q000378:metabolism; D002540:Cerebral Cortex / Q000187:drug effects* / Q000201:enzymology; D002614:Chelating Agents / Q000494:pharmacology; D002712:Chlorides / Q000633:toxicity*; D003676:Deferoxamine / Q000494:pharmacology; D004347:Drug Interactions; D004357:Drug Synergism; D004791:Enzyme Inhibitors / Q000633:toxicity; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008297:Male; D011506:Proteins / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012969:Sodium Fluoride / Q000633:toxicity; D009435:Synaptic Transmission / Q000187:drug effects; D013574:Synaptosomes / Q000187:drug effects / Q000201:enzymology*
D017607:Aluminum Compounds; D001252:Astringents; D002614:Chelating Agents; D002712:Chlorides; D004791:Enzyme Inhibitors; D011506:Proteins; D000077410:Aluminum Chloride; D012969:Sodium Fluoride; D007770:L-Lactate Dehydrogenase; D000251:Adenosine Triphosphatases; D001081:Apyrase; D003676:Deferoxamine; D002118:Calcium