Effects of free Ca2+ on the [Ca2+ + Mg2+]-dependent adenosinetriphosphatase (ATPase) of Alzheimer and normal fibroblasts.
Differences between Alzheimer and control fibroblast [Ca2+ + Mg2+]-dependent ATPase activity at free Ca2+ concentration considerably higher than physiologic concentrations were observed. At 50 microM free Ca2+, Alzheimer and control fibroblast homogenates exhibited maximum velocity values ranging from 8 to 25 nmoles phosphate released/min/mg protein. Higher free Ca2+ (350 microM) inhibited control fibroblast ATPase activity approximately 77%; whereas, Alzheimer fibroblasts retained greater than 75% starting activity. Although the pathophysiological significance of these findings is at present unclear, these data suggest the Ca2+ pump of Alzheimer fibroblasts behaves differently in the presence of high free Ca2+. Such behavior may be of potential diagnostic value.
Rizopoulos
E
E
Brain Research Laboratory of Biochemistry, University of Texas, San Antonio 78285.
Chambers
J P
JP
Wayner
M J
MJ
Martinez
A O
AO
Armstrong
L S
LS
D000544:Alzheimer Disease / Q000201:enzymology*; D017301:Ca(2+) Mg(2+)-ATPase / Q000037:antagonists & inhibitors*; D002118:Calcium / Q000494:pharmacology*; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors*; D002460:Cell Line; D005347:Fibroblasts / Q000201:enzymology; D006801:Humans
D017301:Ca(2+) Mg(2+)-ATPase; D000252:Calcium-Transporting ATPases; D002118:Calcium