Calcium transport by HeLa cell mitochondria.
1. We studied mitochondria of digitonin-permeabilized HeLa cells, since digitonin (60 micrograms/10(6) cells) increases plasma membrane Ca2+ permeability, in order to avoid problems such as low mitochondrial yield and the possibility of obtaining damaged or uncoupled mitochondria from tumor cells. 2. Addition of Ca2+ to digitonin-permeabilized HeLa cells gave rise to a cycle of respiratory stimulation. Ca2+ uptake was almost totally inhibited by antimycin A (6.0 micrograms/ml). 3. Ca2+ release occurred upon addition of carbonyl cyanide p-trifluoromethoxy-phenylhydrazone (FCCP) to digitonin-permeabilized HeLa cells, under steady-state conditions. An antimycin A- and FCCP-insensitive Ca2+ uptake was also detected in this preparation when ATP was added, which reflects Ca2+ capture by other organelles. 4. The characteristics of the mitochondrial Ca2+ transport system in HeLa cells are similar to those of other previously studied tumor cells. Mitochondria from HeLa cells are resistant to the deleterious effects of massive Ca2+ loads.
Caetano
N N
NN
Departamento de Bioquímica, Universidade Federal do Paraná, Curitiba, Brasil.
Campello
A P
AP
Klüppel
M L
ML
Oliveira
M B
MB
D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000378:metabolism*; D002463:Cell Membrane Permeability / Q000187:drug effects; D004072:Digitonin / Q000494:pharmacology; D005260:Female; D006367:HeLa Cells / Q000378:metabolism* / Q000648:ultrastructure; D006801:Humans; D007425:Intracellular Membranes / Q000187:drug effects / Q000378:metabolism; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D010101:Oxygen Consumption / Q000187:drug effects
D004072:Digitonin; D002118:Calcium