ISSN:
1573-6903
Keywords:
NG108-15 cells
;
ATP
;
calcium
;
arachidonic acid
;
spin label
;
membrane fluidity
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract The effect of inhibited bioenergetics and ATP depletion on membrane composition and fluidity was examined in cultured neuroblastoma-glioma hybrid NG108-15 cells. Sodium cyanide (CN) and 2-deoxyglucose (2-DG) were used to block oxidative phosphorylation and anaerobic glycolysis, respectively. Endoplasmic reticulum (ER) Ca2+-pump activity measured by45Ca2+ uptake was 〉92% inhibited in intact cells incubated with CN (1 mM) and 2-DG (20 mM) for 30 min. In addition, exposure of cells to CN and 2-DG caused a 134% increased release of isotopically labeled arachidonic acid (3H-AA) or arachidonate-derived metabolites from membranes. Removal of Ca2+ from the incubation medium ablated the CN/2-DG induced release of3H-AA or its metabolites. Membrane fluidity of intact cells was measured by electron spin resonance spectroscopy using the spin label 12-doxyl stearic acid. The mean rotational correlation time (τc) of the spin label increased 49% in CN/2-DG exposed cells compared to controls, indicating a decrease in membrane fluidity. These results show that depletion of cellular ATP results in inhibition of the ER Ca2+-pump, loss of AA from membranes, and decreased membrane fluidity. We propose that impaired bioenergetics can increase intracellular Ca2+ as a result of Ca2+-pump inhibition and thereby activate Ca2+-dependent phospholipases causing membrane effects. Since neurons derive energy predominantly from oxidative metabolism, ATP depletion during brain hypoxia may initiate a similar cytotoxic mechanism.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00966729
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