The high calcium ion uptake capacity of Ehrlich ascites tumour cell mitochondria is due to inhibition of the permeability transition and phospholipase A2 activity by magnesium.
Tumour cells frequently have a high Ca2+ threshold for the mitochondrial permeability transition which occurs when a large pore in the inner membrane is opened. We studied whether this was due to the known high content of Mg2+ in Ehrlich ascites tumour cell mitochondria or to the increased expression of the protooncogene bcl-2. The latter was found not to be the case. Mg2+ potently inhibited the permeability transition and the binding of Ca2+ to the inner membrane. Also, phospholipase A2 activity was reduced by Mg2+. It is concluded that the high Ca2+ threshold is due to the high Mg2+ content in these tumour mitochondria.
Saris
N E
NE
Department of Anatomy, University of Helsinki, Finland. saris@penger.helsinki.fi
Teplova
V V
VV
Azarashvili
T S
TS
Evtodienko
Y V
YV
Virtanen
I
I
D000098:Acetophenones / Q000494:pharmacology; D000818:Animals; D000906:Antibodies; D015153:Blotting, Western; D002118:Calcium / Q000493:pharmacokinetics*; D002286:Carcinoma, Ehrlich Tumor / Q000188:drug therapy / Q000378:metabolism*; D002477:Cells; D016572:Cyclosporine / Q000494:pharmacology; D007425:Intracellular Membranes / Q000187:drug effects / Q000378:metabolism; D008274:Magnesium / Q000378:metabolism / Q000494:pharmacology*; D051379:Mice; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D010539:Permeability; D010741:Phospholipases A / Q000037:antagonists & inhibitors*; D054467:Phospholipases A2; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000276:immunology
D000098:Acetophenones; D000906:Antibodies; D019253:Proto-Oncogene Proteins c-bcl-2; D016572:Cyclosporine; D010741:Phospholipases A; D054467:Phospholipases A2; D008274:Magnesium; C006821:4-bromophenacyl bromide; D002118:Calcium